Translational biomedical research is often directed to the introduction of a new drug or biologic intended to treat unmet medical need in humans. This unit describes the timing and content of the investigational new drug (IND) application, the primary document required by the U.S. FDA for the initiation of clinical trials in humans with any new chemical entity (NCE) or biologic. The IND application contains all the information necessary for the FDA to make an assessment of the risks and benefits of the proposed clinical trials for the NCE/biologic, containing a detailed but succinct description of the biology, safety, toxicology, chemistry and manufacturing process, and the proposed clinical plan. This unit is geared for those with little or no experience with the IND process and is intended as a global introduction to this, the initial stage of the drug development process for drugs used in humans. Curr. Protoc. Pharmacol. 42:9.10.1-9.10.23. ? 2008 by John Wiley & Sons, Inc.