Summary Prescribing methylphenidate to cocaine addicts with adult adhd is a controversial therapy. The restraint that is recommended in the guidelines is based on experimental research into the addictive nature of methylphenidate. Although very little clinical research has been done so far, in practice the risk of addiction seems limited. There are indications that methylphenidate can have a positive effect on this group. The authors recommend that individual patients with this comorbidity be prescribed methylphenidate in double-blind placebo-controlled conditions, so that the effect of the drug on both disorders can be evaluated objectively.