Illicit and promiscuous use of drugs is a rapidly increasing problem in the United States. This review will concentrate on important medical complications consequent to use of drugs taken solely for pleasure. Opiates. —The heroin problem continues to fester in our large urban centers. Although the number of young persons involved has not altered substantially over the last 15 years, the pattern of heroin abuse has changed. First, although most (70%) of the users are Negroes, Puerto Ricans, or Mexicans living in areas of municipal decay, heroin abuse is no longer confined to school dropouts or to unemployed and underemployed dwellers in urban ghettos. Increasing numbers of cases are being reported in relatively affluent urban and suburban communities as well as among high school and even junior high school students in large cities. Second, the heroin is so flagrantly adulterated that the addict admitted to a medical ward for withdrawal