Cocaine dependence has proved difficult to treat, whether it occurs alone or in combination with opiate dependence. No intervention has been demonstrated to be uniquely effective. Patients might benefit most from combined pharmacotherapeutic and psychotherapeutic interventions. The present study sought to evaluate the feasibility, tolerability, and efficacy of methylphenidate (MP) and cognitive-behavioral group therapy (CBGT) for cocaine dependence in diacetylmorphine-maintained patients. Sixty-two cocaine-dependent diacetylmorphine-maintained patients participated in a dual-site, double-blind, placebo-controlled pilot trial with 4 treatment conditions. The participants were randomly assigned to receive MP or a placebo each combined with either CBGT or treatment as usual for 12 weeks. Methylphenidate 30 mg and a placebo in identical capsules were administered onsite twice daily under supervision in a fixed-dose regimen without titration. Manual-guided CBGT consisted of 12 weekly sessions. Participation in the CBGT sessions was voluntary. Primary outcome measures were retention in pharmacologic treatment, cocaine-free urine samples, self-reported cocaine use, and adverse effects. Urine screens were performed thrice weekly. Seventy-one percent of the participants completed the study protocol. Methylphenidate was well tolerated with similar retention rates compared with the placebo. No serious adverse effects occurred. No difference in cocaine-free urine screens was found across the 4 treatment groups. Self-reported cocaine use was reduced in all 4 study groups. Methylphenidate and CBGT did not provide an advantage over a placebo or treatment as usual in reducing cocaine use. There were no signs of additive benefits of MP and CBGT. Because of the small sample size, the results are preliminary.