The goal of this study was to investigate the safety and utility of labetalol an alpha and beta adrenergic block, for cocaine dependence in humans. A total of 12 subjects were enrolled in this double blind, placebo controlled outpatient study. After baseline measures are obtained, three experimental sessions were held at least 2 days apart. Subjects were administered a single low (100 mg) or high dose of labetalol (200mg) or placebo on each of 3 experimental sessions. The labetalol doses were given in ascending order and the placebo treatment were randomly inserted into the sequence. A single dose of smoked cocaine (0.4 mg/kg) was administered 2 hrs after labetalol or placebo treatment. During the sessions, several subjective, behavioral and physiological measures were obtained.