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The FDA Investigations Operations Manual (IOM) is the primary operational reference for FDA investigators and other field employees, used to perform investigational activities in support of the agency’s public health mission. The current edition is the 2026 IOM, which FDA’s page lists as current as of 07/15/2026. FDA publishes it so that regulated industry can better understand how the agency operates in the field.
Short answer
The IOM is FDA’s internal field handbook, made public. It is organised into ten chapters, from administration and sampling to inspections, imports, recalls and investigator safety. Laboratories, clinics and supply teams can read it to understand what an FDA investigator does on site and which forms are issued when. FDA describes it as a reference written for its own field staff.
Definition and scope
FDA’s own description calls the IOM the primary operational reference for its investigators and other field employees. The agency notes that the manual is primarily used internally by FDA staff, and that it is available publicly so regulated industry and other external stakeholders can better understand FDA operations. The 2026 edition carries the Office of Inspections and Investigations name on its cover.
When citing the manual, name the edition and the currency date FDA shows on its IOM page.
How investigators use it during an inspection
Chapter 5 sets out the inspection framework. An inspection under section 704(a)(1) of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 374) means FDA officers physically entering, at reasonable times and in a reasonable manner, establishments subject to regulation under the Act to determine compliance with applicable FDA requirements. Chapter 5 describes three categories:
- Surveillance (also called routine) inspections.
- Pre-approval, pre-market or pre-license inspections.
- For-cause inspections, used where there is reason to believe a facility has serious manufacturing problems, or to investigate a specific problem or product complaint.
The chapter also states that investigators conduct inspections at reasonable times, within reasonable limits and in a reasonable manner, and display credentials to the most responsible individual onsite.
Forms a facility will see, and when
| Form | What it is | When Chapter 5 says it is issued |
|---|---|---|
| FDA 482 | Notice of Inspection | Signed and issued after the investigator shows credentials; not required for foreign inspections, where credentials are still shown |
| FDA 483 | Inspectional Observations | Upon completing the inspection but before leaving the premises |
| FDA 484 | Receipt for Samples | When any physical sample is collected |
Chapter 5 notes that section 704(a)(4) of the Act gives FDA authority to obtain records “in advance of or in lieu of an inspection”, and that, per CPG Sec. 160.300, evidence obtained in response to a specific written request under section 703 cannot be used in a criminal prosecution of the person from whom it was obtained.
The ten chapters
These are the chapter titles listed on FDA’s IOM page.
| Chapter | Title |
|---|---|
| 1 | Administration |
| 2 | Notes, Records and Information |
| 3 | Regulatory |
| 4 | Sampling |
| 5 | Inspections |
| 6 | Imports |
| 7 | Recall Activities |
| 8 | Investigations |
| 9 | Public Health Collaboration |
| 10 | Safety |
The manual also includes a foreword, a table of contents and an appendix.
Where it matters for labs, clinics and supply decisions
For a facility that handles FDA-regulated products, the inspection chapter is the most direct reading: it shows what an investigator is told to do, in what order the notice, observations and sample receipts appear, and the difference between routine and for-cause visits. FDA gives imports (Chapter 6), sampling (Chapter 4) and recall activities (Chapter 7) their own chapters, so teams that receive products from abroad or sit in a recall chain know where those topics sit in the manual. For how a US trial site is examined, see the FDA BIMO program.
To prepare in practice, see inspection readiness and running a mock FDA inspection. For a related FDA enforcement document, see what an FDA warning letter is. A parallel US lab-inspection reference is the CLIA inspection checklist.
Common misunderstandings
The IOM is a facility checklist
It is not. It is written for FDA’s own field staff, and FDA makes it public so outside stakeholders can understand FDA operations.
A Form FDA 483 is a finding of violation
The IOM describes the 483 as the document providing inspectional findings, titled Inspectional Observations, given before the investigator leaves the premises. It records inspectional observations.
Every inspection is for cause
Chapter 5 lists three categories. For-cause is the one tied to serious manufacturing problems or a specific complaint; surveillance and pre-approval inspections are different categories.
FAQ
What is the FDA Investigations Operations Manual?
It is the primary operational reference for FDA investigators and other field employees, published publicly by FDA. The 2026 edition has ten chapters.
Is the IOM publicly available?
Yes. FDA states that although it is primarily used internally, it is available publicly so industry and other stakeholders can better understand FDA operations.
Which IOM chapter covers inspections?
Chapter 5, Inspections, covers inspection categories, credentials, the FDA 482 Notice of Inspection, the FDA 483 and the FDA 484.
Which IOM edition is current?
FDA’s page is titled 2026 Investigations Operations Manual (IOM) and shows content current as of 07/15/2026.
Sources (checked 2026-10-29)
- FDA, Investigations Operations Manual (IOM), 2026 edition, checked 2026-10-29.
- FDA, IOM 2026, Chapter 5: Inspections (PDF), sections 5.1.1, 5.1.4 and 5.1.4.1 to 5.1.4.2.4, checked 2026-10-29.
