Title 21 of the Code of Federal Regulations
Title 21 is the portion of the Code of Federal Regulations that governs food and drugs within the United States for the Food and Drug Administration (FDA), the Drug Enforcement Administration (DEA), and the Office of National Drug Control Policy (ONDCP).
It is divided into three chapters:
Most of the Chapter I regulations are based on the Federal Food, Drug, and Cosmetic Act.
- 11 — electronic records and electronic signature related
- 50 Protection of human subjects in clinical trials
- 54 Financial Disclosure by Clinical Investigators 
- 56 Institutional Review Boards that oversee clinical trials
- 58 Good Laboratory Practices (GLP) for nonclinical studies
The 100 series are regulations pertaining to food:
- 101, especially 101.9 — Nutrition facts label related
- 106-107 requirements for infant formula
- 110 et seq. cGMPs for food products
- 111 et seq. cGMPs for Dietary Supplements
- 170 food additives
- 190 dietary supplements
The 200 and 300 series are regulations pertaining to pharmaceuticals :
- 202-203 Drug advertising and marketing
- 210 et seq. cGMPs for pharmaceuticals
- 310 et seq. Requirements for new drugs
- 328 et seq. Specific requirements for over-the-counter (OTC) drugs.
The 500 series are regulations for animal feeds and animal medications:
- 510 et seq. New animal drugs
- 556 Tolerances for residues of drugs in food animals
The 600 series covers biological products (e.g. vaccines, blood):
- 601 Licensing under section 351 of the Public Health Service Act
- 606 et seq. cGMPs for human blood and blood products
The 700 series includes the limited regulations on cosmetics:
- 701 Labeling requirements
The 800 series are for medical devices:
- 803 Medical Device Reporting
- 814 Premarket Approval of Medical Devices 
- 820 et seq. Quality system regulations (analogous to cGMP, but structured like ISO) 
- 860 et seq. Listing of specific approved devices and how they are classified
The 900 series covers mammography quality requirements enforced by CDRH.
The 1000 series covers radiation-emitting device (e.g. cell phones, lasers, x-ray generators); requirements enforced by the Center for Devices and Radiological Health. It also talks about the FDA citizen petition.
The 1100 series includes updated rules deeming items that statutorily come under the definition of "tobacco product" to be subject to the Federal Food, Drug, and Cosmetic Act as amended by the Tobacco Control Act. The items affected include E-cigarettes, Hookah tobacco, and pipe tobacco.
The 1200 series consists of rules primarily based in laws other than the Food, Drug, and Cosmetic Act:
- 1240 Rules promulgated under 361 of the Public Health Service Act on interstate control of communicable disease, such as:
- 1271 Requirements for human cells, tissues, and cellular and tissue-based products (i.e. the cGTPs).
- "CFR Title 21". US FDA. Retrieved February 2014. Check date values in:
- Food and Drug Administration (2008). "Subchapter A — General: Financial Disclosure by Clinical Investigators". Retrieved 9 April 2009.
- Food and Drug Administration (2008). "Subchapter H — Medical Devices: Part 814 Premarket Approval of Medical Devices". Retrieved 9 April 2009.
- Food and Drug Administration (2008). "Subchapter H — Medical Devices: Part 820 Quality System Regulation". Retrieved 9 April 2009.
- "Extending Authorities to All Tobacco Products, Including E-Cigarettes, Cigars, and Hookah". FDA.gov. United States Food and Drug Administration. Retrieved 11 May 2016.
- Title 21 of the Code of Federal Regulations (current "Electronic CFR")