The 472 subjects accounted for 1,303 commitments to the hospital during the 7-year period and represented patients whose prison sentences had not expired by the end of the study period so that patients with diverse crimes and varying sentence lengths could be studied. Presenting symptoms and behaviors described by referring psychiatrists to document inmates' need for commitment were analyzed. The relation between medication refusal and indicators of hospital utilization during imprisonment was then explored. Analysis of the commitment rationale for inmates revealed that medication refusal, threatened or potential violent behavior toward others, and hallucinations or delusions were the major reasons used to justify admission and readmission. Medication refusal was associated with a greater number of hospitalizations, shorter hospitalizations, diagnoses of paranoid schizophrenia, longer prison sentences, and convictions for more serious felonies. Inmates admitted for medical refusal were also likely to be referred concurrently for threatened or potential violent behavior toward others. The study demonstrates the particularly violent nature of a large proportion of hospitalized mentally ill inmates and the important role of medication refusal in their rehospitalization. 33 references, 1 table.