The authors conducted a 16-week study with nine opioid-dependent individuals (six male; four white/two African American/three Hispanic; age 36.8 +/- 2.2 years). Participants were assigned to either a low-dose (165 mg/week; n = 5) or high-dose (330 mg/week; n = 4) Levo-alpha-acetylmethadol (LAAM) condition according to a randomized, double-blind, within-subjects crossover design, such that they were inducted onto one maintenance dose for 4 weeks and then were crossed over to receive the converse for 4 weeks. Subsequently, individuals underwent detoxification from LAAM. Eight of nine participants completed the study protocol. The proportion of urine samples positive for opiates was 0.22 +/- 0.08 and 0.53 +/- 0.12, under the high- and low-dose conditions, respectively (F = 11.8; P = 0.01). These results show that LAAM dose regimen affects the degree of abstinence from opioids.