One hundred and twelve drug abusers admitted to Bellevue Psychiatric Hospital were studied from a social, motivational, psychiatric, and pharmacological view. Heroin users were usually sociopathic and were costing the city $10 million a day in crimes to support their habit. Emotionally disturbed but younger groups tended to use marihuana, amphetamines, and hallucinogens. Fifty percent of this group were considered to be schizophrenic before taking drugs and 37% required state hospitalization. Thus, protracted psychotic states thought to be due to drug ingestion may be due to preexisting mental disturbances. A desire for euphoria, possibly stemming from underlying depression, was most frequently the reason given for drug abuse. Influences by friends or environment was the second most frequent reason. Almost all patients had experiences with drugs other than the one which caused admission to the hospital.