Despite the large number of elderly patients in nursing homes and the intensity of medication use there, few current data are available on patterns of medication use in this setting. We studied all medication use among 850 residents of 12 representative intermediate-care facilities in Massachusetts. Data on all prescriptions and patterns of actual use were recorded for all patients during one month. On average, residents were prescribed 8.1 medications during the month (interquartile range, 7.4 to 8.8) and actually received 4.7 (range, 4.2 to 5.4) medications during this period. More than half of all residents were receiving a psychoactive medication, with 26% receiving antipsychotic medication. Twenty-eight percent of patients were receiving sedative/hypnotics during the study month, primarily on a scheduled rather than an as-needed basis. Of patients receiving a sedative/hypnotic, 26% (range, 14% to 41%) were taking diphenhydramine hydrochloride, a strongly anticholinergic hypnotic. Of those receiving one of the benzodiazepines, 30% were receiving long-acting drugs, generally not recommended for elderly patients. The typical benzodiazepine dose was equivalent to 7.3 mg per patient per day of diazepam. The most commonly used antidepressant was amitriptyline hydrochloride, the most sedating and anticholinergic antidepressant in common use. These data indicate that despite growing evidence of the risks of psychoactive drug use in elderly patients, the nursing home population studied was exposed to high levels of sedative/hypnotic and antipsychotic drug use. Suboptimal choice of medication within a given class was common, and use of standing vs as-needed orders was often not in keeping with current concepts in geriatric psychopharmacology. Additional research is needed to assess the impact of such drug therapy on cognitive and physical functioning, as well as to determine how best to improve patterns of medication use in this vulnerable population.