Results of preclinical studies suggest that pergolide, a mixed D(1)/D(2) dopamine receptor agonist, may be useful in treating cocaine dependence. To empirically investigate this possibility, we conducted a 5-year, double-blind, placebo-controlled clinical trial of two doses of pergolide (0.05 and 0.25 mg bid) in subjects with cocaine dependence and combined cocaine/alcohol dependence. Data analysis was performed on an intent to treat population (N=358) and a per protocol population (N=108) with urine drug screens (UDS) used as the main outcome measure. There were no significant effects on UDS at either pergolide dose. Pergolide had no significant effect on alcohol use in the comorbid alcohol/cocaine dependence group. Pergolide does not appear to have clinical value in the treatment of cocaine dependence or in decreasing alcohol use in cocaine-dependent individuals at the presently studied doses.