Written and maintained by CASRAI Editorial Board
Last updated
Quick answer: Vancouver style is the numbered-citation format the International Committee of Medical Journal Editors (ICMJE) points authors to in its “Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals.” References are numbered consecutively in the order they first appear in the text, cited with Arabic numerals, and listed in that same citation-order (not alphabetically) in the reference list. ICMJE does not spell out every formatting detail itself — it directs authors to the National Library of Medicine’s (NLM) Citing Medicine, 2nd edition, and its Sample References page for the specifics below.
Vancouver style at a glance
| Element | Vancouver/ICMJE rule |
|---|---|
| In-text citation | Arabic numeral per ICMJE’s own wording, “identify references in text, tables, and legends by Arabic numerals in parentheses.” Many journals instead use superscript numerals — this is a common, accepted journal-level variation, so always check the target journal’s own instructions to authors. |
| Citation order | Numbered consecutively in the order each source is first mentioned in the text, not alphabetically. |
| Reference list order | Same order as the in-text numbers (citation order), not alphabetical by author. |
| Author listing | List all authors up to six. For seven or more authors, list the first six followed by “et al.” |
| Journal name | Abbreviated using NLM/PubMed journal-title abbreviations (the same abbreviations used in NLM Catalog and MEDLINE/PubMed), not spelled out in full. |
| Article title | Sentence case, no italics, no quotation marks. |
| Journal title | Not italicized (unlike APA or MLA). |
| Governing source | NLM’s Citing Medicine, 2nd edition, and its Sample References page — ICMJE Recommendations defer to these for exact formatting rather than restating every rule. |
In-text citation format
Each source gets a number the first time it is cited in the text, and that same number is reused every subsequent time the source is cited — it is never renumbered. ICMJE’s Recommendations state the base rule directly: references are identified “by Arabic numerals in parentheses.” In practice, a large share of biomedical journals instead render the numeral as a superscript rather than a parenthetical numeral — both are within the Vancouver family, and which one a given manuscript should use is a journal-specific house-style decision, not something Vancouver/ICMJE mandates uniformly. Check the target journal’s instructions for authors before submitting, since a manuscript formatted with the wrong in-text convention is a common, easily avoidable revision request.
Multiple sources cited at the same point are typically given as a range or comma-separated list of numerals (for example, citing sources 3 through 5 plus source 9 might appear as “[3-5,9]” or as superscript “3-5,9”), following the same numeral-based logic — exact punctuation again varies slightly by journal.
Reference list format rules
Author names
List authors by last name followed by initials, with no periods after initials and no comma before the initials (for example, “Halpern SD”). List every author up to six. When a work has seven or more authors, list the first six names and add “et al.” after the sixth. This six-author threshold is the NLM/Vancouver convention specifically — it is not universal across numbered citation styles; the AMA Manual of Style (11th edition), a separate and more prescriptive style used by JAMA and the JAMA Network journals, lists up to six authors but switches to “et al.” after only the first three for a seven-or-more-author work. Vancouver and AMA are often confused because both trace back to the same medical-editing tradition, but a reference formatted correctly in one will not automatically pass in the other — see the full breakdown on et al. citation rules across styles.
Journal titles
Journal names are abbreviated, not spelled out, using the standard NLM/PubMed abbreviation for that journal (the same abbreviation format used in the NLM Catalog and displayed in PubMed/MEDLINE records) — for example, New England Journal of Medicine becomes “N Engl J Med.” The journal abbreviation is not italicized in Vancouver style. Authors preparing a manuscript can look up a journal’s official NLM abbreviation directly in the NLM Catalog rather than guessing or abbreviating by convention, since inconsistent or incorrect abbreviations are a common source of reference-list errors flagged at copyediting.
Punctuation and structure
A standard journal-article reference follows this sequence: authors, article title (sentence case, no italics), abbreviated journal name, year, volume, issue in parentheses, and page range — for example:
Halpern SD, Ubel PA, Caplan AL. Solid-organ transplantation in HIV-infected patients. N Engl J Med. 2002 Jul 25;347(4):284-7.
And for a source with more than six authors:
Rose ME, Huerbin MB, Melick J, Marion DW, Palmer AM, Schiding JK, et al. Regulation of interstitial excitatory amino acid concentrations after cortical contusion injury. Brain Res. 2002;935(1-2):40-6.
Both examples are drawn from NLM’s own published Vancouver/Uniform Requirements sample references.
Reference templates and worked examples by source type
| Source type | Template | Worked example |
|---|---|---|
| Journal article (1-6 authors) | Author AA, Author BB. Article title. Abbreviated Journal Name. Year;Volume(Issue):Pages. | Halpern SD, Ubel PA, Caplan AL. Solid-organ transplantation in HIV-infected patients. N Engl J Med. 2002 Jul 25;347(4):284-7. |
| Journal article (7+ authors) | First six authors, et al. Article title. Abbreviated Journal Name. Year;Volume(Issue):Pages. | Rose ME, Huerbin MB, Melick J, Marion DW, Palmer AM, Schiding JK, et al. Regulation of interstitial excitatory amino acid concentrations after cortical contusion injury. Brain Res. 2002;935(1-2):40-6. |
| Book | Author AA, Author BB. Book title. Edition. Place of publication: Publisher; Year. | Murray PR, Rosenthal KS, Kobayashi GS, Pfaller MA. Medical microbiology. 4th ed. St. Louis: Mosby; 2002. |
| Website / webpage | Site or organization name [Internet]. Place: Publisher; copyright year [cited access date]. Available from: URL. | eatright.org [Internet]. Chicago: Academy of Nutrition and Dietetics; c2016 [cited 2016 Dec 27]. Available from: https://www.eatright.org/. |
All four templates and examples above are reproduced from NLM’s own published Vancouver/Uniform Requirements reference-formatting page, verified directly against nlm.nih.gov on 2026-08-16.
For source types not shown above, follow the same authors–title–container–date logic and check NLM’s Citing Medicine Sample References page directly, since Vancouver/NLM covers dozens of specific source types (conference papers, theses, government reports, audiovisual material, and more) in more detail than fits a single overview. Two related, non-print source types have their own dedicated CASRAI guides: citing a preprint (including Vancouver format) and citing a dataset.
DOIs and where they go
ICMJE Recommendations do not fix a single DOI placement rule — this is one of the areas where “Vancouver style” functions as a shared, evolving family of conventions rather than one rigid rulebook, and exact DOI formatting is one of the more common points of journal-to-journal variation within it. Where a journal’s own author instructions specify a DOI convention (commonly appended at the end of the reference as “doi:10.xxxx/xxxxx” or the resolver-link form “https://doi.org/10.xxxx/xxxxx”), follow that journal’s stated convention exactly rather than a generic template — see DOI for background on the identifier itself.
Vancouver vs. AMA vs. IEEE: three numbered styles compared
Vancouver/ICMJE is one of several numbered-citation families, and the three are frequently mixed up because they share the core mechanic (sequential numbering, citation-order reference list). They differ in the details:
| Vancouver / ICMJE (NLM) | AMA (11th ed.) | IEEE | |
|---|---|---|---|
| Typical field | Biomedical and clinical journals broadly | JAMA and the JAMA Network journals specifically | Engineering, computer science, electronics |
| Author cutoff before “et al.” | First 6 of 7+ authors | First 3 of 7+ authors | Style-guide dependent; commonly all authors or “et al.” after 6, per publisher |
| In-text format | Parenthetical Arabic numeral per ICMJE (superscript common in practice, journal-dependent) | Superscript numeral, standard | Square brackets, e.g. [1] |
| Reference list order | Citation order | Citation order | Citation order |
For the full seven-style comparison across author-date and numeric systems, see Citation Styles and Referencing Formats: A Practical Overview. For the underlying interoperability standard several reference managers implement to support numbered styles like Vancouver, see NISO Z39.29 (Bibliographic References).
Common Vancouver-style errors to check before submission
- Alphabetizing the reference list. Vancouver references are ordered by first-citation order in the text, not alphabetically by author surname — a common mistake when a manuscript is drafted with a reference manager defaulted to an author-date style and switched late.
- Renumbering a repeated citation. A source cited a second or third time keeps its original number; it does not get a new one.
- Spelling out journal titles in full. Vancouver uses NLM-standard journal abbreviations, not full titles.
- Italicizing the journal name or article title. Neither is italicized in Vancouver style (unlike APA, which italicizes the journal title and volume number).
- Using the wrong et al. threshold. Confirm whether the target journal actually follows Vancouver’s six-author cutoff or AMA’s three-author cutoff — both are numbered biomedical styles and it is easy to apply the wrong one.
- Mismatched in-text and reference-list numbering. This typically surfaces when references are reordered or deleted late in drafting without renumbering every in-text citation to match — check this specifically after any late-stage edit that adds, removes, or reorders sources.
Frequently asked questions
What is Vancouver referencing style?
Vancouver style is a numbered citation format used mainly in biomedical and clinical journals. Sources are numbered in the order they are first cited in the text, cited in-text with that number, and listed in the reference list in the same citation order rather than alphabetically. It takes its name from a 1978 meeting of medical journal editors in Vancouver, which became the group now known as ICMJE.
Is Vancouver style the same as ICMJE style?
They are closely linked but not identical terms. ICMJE is the editorial body whose Recommendations point authors to Vancouver/NLM conventions for reference formatting; ICMJE itself does not publish a complete, independent style manual for every reference type, instead deferring to NLM’s Citing Medicine. In practice, “Vancouver style” and “ICMJE reference format” are used interchangeably.
How many authors do you list before “et al.” in Vancouver style?
List up to six authors in full. For a work with seven or more authors, list the first six and add “et al.” after the sixth.
Do you use superscript numbers or numbers in parentheses in Vancouver style?
ICMJE’s own Recommendations describe Arabic numerals in parentheses, but many journals that follow Vancouver conventions use superscript numerals in practice. This is a journal-level house-style choice — check the specific journal’s instructions for authors rather than assuming either format.
What is the difference between Vancouver and AMA style?
Both are numbered biomedical citation styles that trace back to the same editorial tradition, but they are governed by different bodies and diverge on details — most notably, Vancouver lists the first six authors before “et al.” on a seven-plus-author work, while AMA (11th edition) lists only the first three. Always confirm which specific style a journal requires by name.
How do you abbreviate journal names in Vancouver references?
Using the journal’s official NLM/PubMed abbreviation, findable in the NLM Catalog or on the journal’s PubMed/MEDLINE record — not an ad hoc abbreviation.
Can reference-management software format Vancouver citations automatically?
Yes — Zotero, Mendeley, and EndNote all include a Vancouver (or “Vancouver superscript”) citation style that can be applied automatically, though it is still worth spot-checking author counts, journal abbreviations, and DOI placement against the target journal’s actual published references, since style-file implementations can drift from a journal’s current house style. See Zotero vs. Mendeley for a comparison of the two most common free options.
Last verified 2026-08-16 against ICMJE’s Recommendations (icmje.org) and NLM’s Uniform Requirements/Vancouver sample-reference page (nlm.nih.gov/bsd/uniform_requirements.html). ICMJE and NLM periodically revise wording and examples; re-check both primary sources directly if citing this page’s specifics more than about 12 months from that date.
