Completion rates for outpatient opioid detoxification with clonidine generally range from 20-40%, but few studies have examined the correlates of successful completion. Of 29 consecutive patients, we compared those who completed detoxification with clonidine (n=12) to those who did not (n=17). Patients who completed treatment were significantly (p< 0.05) more likely to depend on opioids other than heroin, have private health insurance, and report low levels of subjective withdrawal symptoms. Patients with two or three of these characteristics were about seven times more likely to complete treatment than patients with none or one. Although it may not detoxify most opioid-dependent patients, clonidine will likely play a continued role in selected patients when a non-narcotic agent is desirable. The study findings may help target patients who could benefit the most from outpatient clonidine detoxification.