The abuse of cocaine, which is increasing in the United States, is related to a number of medical problems, some of which are as yet poorly understood. Its most important action is its ability to block the initiation or conduction of the nerve impulse following local application. In this paper, some of the lesser-known medical complications that have been associated with the use of the drug are reviewed. These include cardiac dysfunction and sudden death, neurologic and psychiatric complications, pulmonary complications, and nutritional disorders.