The efficacy of naltrexone as a treatment for concurrent alcohol abuse or dependence and pathological gambling was evaluated in a randomized, double-blind, placebo-controlled trial. Fifty-two, mostly male, subjects were recruited from the community and received 11 weeks of medication during which cognitive-behavioral counseling was also provided. No significant group differences were found on any alcohol or gambling variable (ie, frequency, quantity, expenditures) at post-treatment or at the one year follow-up. However, a strong time effect was found suggesting that treatment, in general, was effective. The use of naltrexone to treat concurrent alcohol use and gambling problems was not supported.