The development of drug and biological products intended to treat rare diseases (Orphan diseases) is one of the fastest growing areas of clinical research, and also one of the most challenging. This article provides an introduction to two important regulatory considerations for Orphan drugs: Orphan status designations and general considerations for the administration of investigational agents in early phase clinical trials. Incentives available to orphan drug developers under the Orphan Drug Act (ODA) and requirements for obtaining an orphan status designation are discussed. An introductory overview of ethical and statutory considerations for investigational drugs, requirements for initiating investigational new drug applications (INDs), and sources of information and advice from the US Food and Drug Administration (FDA) are also described.