Cognitive-behavioral therapy (CBT) depends on adequate cognitive functioning in patients, but prolonged cocaine use may impair cognitive functioning. Therefore, cognitive impairment may impede the ability of cocaine abusers to benefit from CBT. To begin to address this issue, we investigated the relationship between cognitive impairment and two treatment outcomes, therapy completion and abstention. Eighteen carefully screened non-depressed cocaine-dependent patients in a psychopharmacological clinical trial were administered the MicroCog computerized battery to assess cognitive performance at treatment entry. T-tests were used to compare cognitive functioning between completers (patients remaining in treatment at least 12 weeks) and dropouts. The results indicated that treatment completers had demonstrated significantly better cognitive performance at baseline than patients who dropped out of treatment. Cognitive domains that significantly distinguished between treatment completers and dropouts were attention, mental reasoning and spatial processing. This study provides preliminary evidence that cognitive impairments may decrease treatment retention and abstinence in CBT of cocaine dependence.