Twenty-six children having Attention Deficit Hyperaclivity Disorder were tested before and after treatment with methylphenidate. In addition to standardized parent and teacher rating scales, each child was assessed on a variety of psychomotor tests with an emphasis on attentional constructs. Relatively few of the performance tests, administered prior to medication, predicted clinical response to medication. However, chronological age and performance on a memory distraction task and on the Graduated Holes Task (Kløve, 1963) were moderately correlated with clinical outcome. Using stepwise multiple regression analyses to predict outcome, age and the psychomotor tasks predicted about 50% of outcome variance. There was virtually no relationship between clinical change and change on the performance tests. Findings are discussed with respect to results from previous prediction studies, theoretical models of drug response, and clinical management. © 1991 Plenum Publishing Corporation.