A history of childhood attention-deficit/hyperactivity disorder (ADHD) is a mandatory prerequisite for the diagnosis of adult type ADHD, for which no DSM criteria exists. Since the diagnosis must be made retroactively, tentative criteria have been designed to establish the presence of the childhood disorder. In the 1970s, I advanced the hypothesis that "minimal brain dysfunction" (as ADHD was called) might be produced by decreased catecholaminergic function. A total of over 300 ADHD patients have been included in treatment studies, including 224 patients who received stimulants in four double-blind, placebo-controlled trials: three of methylphenidate (N = 176) and one of pemoline (N = 48). An additional 79 patients have been included in open-label trials of pargyline, selegiline, bupropion, levodopa, phenylalanine, and tyrosine. Altogether, these studies have demonstrated the efficacy of methylphenidate, pemoline, and monoamine oxidase-B (MAO-B) inhibitors when administered to adult ADHD patients; a robust response was produced in 60% of the patients. Bupropion and selegiline were effective in the open-label studies and should be systematically evaluated. A long-term study is being conducted with methylphenidate maintenance; patients have been followed for as long as 5 years, and little, if any, drug tolerance has been observed. Treatment of adult patients who have ADHD is symptomatic, not curative, but the combination of medication and psychotherapy may offer life-changing opportunities to individuals who suffer from the disorder.