The Food and Drug Administration (FDA) in the United States has multiple roles. The primary responsibilities for oncology drug products are the supervision of clinical research, the evaluation of marketing claims for new and previously approved drugs, the granting of exclusive marketing licenses for approved claims, and the monitoring of post-marketing activity for safety. Additional roles include providing incentives for developing products for rare diseases and children. The principles used for monitoring clinical studies are based on science, law and ethical guidelines. The principles used for evaluation of evidence to support marketing claims are based in science, law, regulation, and frequently the advice of a panel of external experts. Approved products should demonstrate patient benefit that is commensurate with the probable risks. The types of endpoints and their advantages and disadvantages for regulatory review are discussed. There are regulatory options available for conditional approval based on surrogate endpoints that are likely to predict patient benefit, a mechanism for reducing the time to review an application for indications with no known effective therapy, and procedures for providing access to patients for unapproved drugs.