The authors prospectively monitored 60 consecutive admissions to an inpatient psychiatry service to determine the role of drugs in psychiatric hospitalization. They categorized drug-related problems as 1) drug intoxication, 2) drug abuse, 3) side effects of therapeutic drugs, and 4) noncompliance with prescribed medications. During the 6-month study 25 (41.7%) of the admissions were related to drug use; in 16 (26.7%) admissions a drug-related problem was identified as the primary cause of hospitalization. Alcohol was involved in 8 admissions, and Fiorinal, cocaine, and flurazepam were each related to 2 admissions.