Criminal profiles have long been used by federal law enforcement officials to aid in the detection and apprehension of individuals suspected of criminal activity. Profiles were developed initially in the early 1970's to detect terrorists and foil airplane hijackers. Since then, the use of criminal profiles has expanded to play an increasingly important role in the war on drugs being waged by federal, state, and local police on highways and in bus stations and air terminals. This paper reviews the development of criminal profiles, with emphasis on the drug courier profiles, and analyzes the legal issues surrounding their use. Questions are raised as to the composition of the profiles, the constitutionality of their application, and their reliability and effectiveness in identifying drug couriers.