In an attempt to develop a new opiate detoxification approach, the authors assessed the efficacy of buspirone in the treatment of acute heroin withdrawal. Buspirone, a drug interacting with the serotonergic system, was selected because there is evidence that a decrease in serotonergic neurotransmission may be involved in opiate withdrawal symptoms. Twenty-nine hospitalized heroin addicts were randomized to 4 groups: (1) placebo; (2) methadone; (3) buspirone 30 mg daily; (4) buspirone 45 mg daily. The double-blind trial started in all patients with a 5-day methadone stabilization period ending with a 30-mg dose. This was followed from days 6 through 12 by placebo in group 1 and by a methadone taper in group 2. Because of its delayed action, buspirone was started on day 1 in groups 3 and 4 and was continued, after methadone discontinuation, through day 12. On day 13, drugs and placebo were discontinued and patients were observed through day 14. Withdrawal symptoms were assessed with the "Subjective Opiate Withdrawal Scale" (SOWS) and the "Objective Opiate Withdrawal Scale" (OOWS). The SOWS and OOWS scores were significantly higher in the placebo group than in the methadone, buspirone 30 mg, and buspirone 45 mg groups. There were no significant differences in SOWS or OOWS scores when the methadone group was compared with each of the two buspirone groups or when the two buspirone groups were compared with one another. In conclusion, buspirone, a nonopiate drug with no abuse potential, a safe side effect profile and no withdrawal symptoms, at doses of 30 and 45 mg, was as effective as a methadone taper in alleviating the withdrawal symptoms of heroin addicts stabilized for 5 days with, and then withdrawn from, methadone. The use of buspirone could be particularly helpful in outpatient settings where the duration of the methadone taper recommended for detoxification can be lengthy.