Objective: To test if visual focusing and mimic display as features of self-regulation in ADHD children show a curvilinear relation to rising methylphenidate (MPH) doses. To test if small dose steps of 2.5mg MPH cause significant changes in behavior. And to test the relation of these features to intellectual performance, parents' ratings, and clinical outcome. Method: Twenty-five children of a clinical convenience sample are filmed playing cards and doing oral arithmetic exercises without medication and after intake of MPH raised in steps of 2.5 mg. Recordings are revised by four blinded raters counting visual focus loss and rating the variability of patients' smile. Results: All hypotheses are confirmed. Best self-regulation coincides with best intellectual performance, highly significant improvement in parents' ratings, and good clinical outcome. Conclusion: The procedure could be helpful for MPH dose finding in the physician's practice and make therapy more efficient by means of a more precise dosage. (Contains 1 table and 3 figures.)