The pharmacologic profile of sublingual and subcutaneous buprenorphine, a partial opioid agonist, indicates it may be useful as a maintenance drug in the treatment of opioid dependence. However, illicit intravenous self-administration suggests that it may have a greater abuse potential by this route of administration. Physiologic and subjective effects of intravenous buprenorphine (0.0, 0.3, 0.6, and 1.2 mg) were determined in a dose-escalation study in six nondependent volunteers with histories of opioid use. Buprenorphine caused miosis and decreased respiratory rate, increased diastolic blood pressure, and transiently increased heart rate. Buprenorphine increased positive responses on a "feel drug" question and scores on scales of "liking," "good effects," euphoria, and apathetic sedation. Physiologic and subjective responses were not consistently dose related, a finding compatible with the pharmacologic profile of a partial agonist. The findings indicate that buprenorphine has substantial potential for abuse when administered intravenously.