This review attempts to summarize the literature on the effects of drugs on isolation-induced aggression in mice. In spite of the fact that each investigator that was surveyed utilized different methodologies (e.g., induction techniques, testing conditions, scoring systems), the results from the various laboratories are generally in agreement in many respects. Fighting in isolated mice has been shown to be selectively antagnoized (i.e., antifighting activity at doses significantly below doses producing neurological impairment in isolated mice) by antidepressants, neuroleptics, anticholinergics, antiserotonergics, and antihistamines; however, aggression was nonselectively antagonized by anxiolytics, muscle relaxants, anticonvulsants, sedatives, and hypnotics. Emphasis is placed on the necessity to determine pharmacological selectivity whenever antagonistic effects are observed; this can only be accomplished by measuring neurological impairment (ataxia) in the isolated mice by utilizing a test such as an inclined-screen, preferably immediately following aggression testing. Since isolated mice have been shown to exhibit marked differences in drug sensitivities and in metabolic dispositions of many classes of drugs as compared to group-housed controls, statements concerning drug selectivity or specificity are meaningless without some evidence for a lack of neurological impairment in isolated, aggressive mice.