A partial blockade of the multiple actions of cocaine is one strategy by which cocaine dependence may be treated. Risperidone, a 5-hydroxytryptamine and dopamine D2 antagonist, is an atypical antipsychotic and was a candidate medication for the treatment of cocaine dependence. One hundred ninety-three cocaine-dependent subjects were enrolled in a 12-week, randomized, double- blind, placebo-controlled trial. Subjects initially received either placebo or 4 or 8 mg of risperidone, with a subsequent change to active doses of 2 mg and 4 mg. Subjects attended the clinic twice each week, provided urine samples, obtained medication, and underwent one behavioral therapy session per week. The study was terminated at the interim analysis. Retention was worse for the 4- and 8-mg active medication groups. Side effects were primarily associated with the 8-mg dose, although neither 2 mg nor 4 mg was well accepted by subjects. There was no reduction in cocaine use associated with risperidone. The results suggest that although antagonists might be a useful treatment approach, such as in the treatment of opiate dependence, risperidone is unlikely to find broad acceptance with the treatment-seeking population.