Seventy institutionalized severely and profoundly retarded patients were administered intramuscular butorphanol, 1.0 to 4.0 mg, for premedication prior to dental procedures. These patients had been refractory to previous combined chloral hydrate and diphenhydramine treatment. Clinical efficacy was categorized according to the extent that adjunctive restraints were required to accomplish the dental procedure. A total of 151 butorphanol trials were recorded. Butorphanol was observed to be clinically effective in 74.8% of the administrations and sedation was observed in 28.2% of the trials. Dosage titration increased efficacy to 85.0%. Contribution of concurrent central nervous system depressant medication to clinical efficacy and dose requirements lacked statistical significance; however, a strong trend (p = 0.068) was found in the medication-free group with higher dosage. Vomiting (2.6%) was the most frequent adverse effect observed. One patient had marked cardiorespiratory depression that was promptly reversed by intravenous naloxone. Two patients experienced mild hypotensive episodes immediately following injection, but they recovered uneventfully. Butorphanol was shown to be a safe and effective agent for dental premedication in this difficult patient population.