Neuropsychological assessment of substance abusers frequently proves useful for the evaluation of those aspects of cognitive functioning that may be relevant for optimal therapeutic management and treatment planning. Research has demonstrated the presence of neuropsychological impairment in chronic abusers of CNS depressants, including alcohol, as well as opiates and possibly cocaine, especially when such substances are combined in a polydrug pattern of abuse. Clinical neuropsychological evaluation of individual substance abusers should take into account the various personal, demographic and neuromedical background variables that can affect cognitive functioning. Efforts should be made to distinguish between acute drug effects and more longterm stable deficits that may not become apparent for some time. Neuropsychological referrals should be made, and measures selected to answer particular questions about neurocognitive functioning that are relevant to treatment and eventual overall adjustment. A neuropsychological review of systems is likely to show a pattern of impairment in substance abusers that involves the integration of different cognitive functions for effective problem solving. Strongly focal or lateralized deficit patterns are less likely to be the result of drug abuse alone, and should prompt the appropriate neuromedical follow-up.