Anger and temper outbursts can be serious clinical problems after brain injury. This study used a randomized, pretest, posttest, placebo control group, single-blind design to evaluate the therapeutic usefulness of methylphenidate to control brain-injury-related anger. The 38 subjects in the study were young adult males who had sustained serious brain injuries and who were beyond the period of rapid, spontaneous recovery. The subjects were divided into two groups, one that received 30 mg of methylphenidate per day and the placebo control group. A comparison of the drug group with the placebo group before and at the end of the six-week treatment period on all the anger outcome measures analyzed simultaneously with multivariate analysis indicated a significant drug-by-time interaction effect, F(4.33) = 5.29, p = .002, demonstrating the therapeutic effect of methylphenidate on anger. The study found that drug responders could be predicted by pretreatment level of anger with a .09 probability of misclassification. Methylphenidate also significantly reduced impairment on all of the general psychopathology outcome measures (F[3.31] = 5.42, p < .01). The drug improved memory for those subjects in the treatment response group but did not result in changes on measures of attention, nor did it have an effect on a checklist of subjective side effects, suggesting that it has minimal or absent cognitive toxicity and is likely to be tolerated well by individuals with brain injuries.