Although the average physician can generally expect to see at least one alcoholic everyday, alcoholism is one of the most poorly diagnosed of the common illnesses. Alcoholism has supplanted syphilis as the great imitator of other diseases and produces measurable damage in every bodily system. The clues that the body presents, while not diagnostic in themselves, should alert physicians to the possibility of the alcobolism diagnosis. The author discusses some of the stereotypes and definitions that have added to the problem of reaching an alcoholism diagnosis, the importance of distinguishing betweenprimary and secondary alcoholism, and the clues that may present both during a physician's history-taking session and in an examination. He concludes by discussing how to present the diagnosis to the patient.