During the 3-month period of the study, 29,633 medication doses were dispensed, 5.8 percent of which were refused; 62 percent of the patients refused at least one dose during this period of time. Antipsychotic medication was most frequently refused, followed by antiparkinsonian, antianxiety, antidepressant, antibiotic, and analgesic medications. A total of 31 percent of the subjects refusing medication did so because of negative side effects. Inmates who had actually experienced negative side effects from the medication were significantly more likely to refuse doses than those who had not. About 20 percent of the inmates refused doses because they saw no need or benefit in taking the medication, and small numbers of subjects refused doses for a variety of other reasons such as paranoid fears about prescription motives, concern over medication errors, and attempts to use refusal as a means for communicating with doctors. Refusal rates were highest on Mondays and lowest on Fridays, possibly related to the mood of treatment staff beginning and ending their work week. No demographic differences were found between inmates refusing medication and those accepting it, although subjects serving life sentences were less likely to refuse medication than those who were not. Fourteen references are included.