We compared the short-term efficacy of a high-dose, 3 day regimen of buprenorphine to a standard 5-day course of clonidine in attenuating the signs and symptoms of the acute opioid abstinence syndrome during rapid detoxification from heroin in 25 men and women admitted to a closed inpatient research ward for this randomized, double-blind, parallel-group trial. Among the 18 completers, there were no significant differences between the buprenorphine and clonidine groups on five subjective and six physiological measures. However, clonidine lowered blood pressure and buprenorphine provided more effective early relief of withdrawal symptoms.