Pharmacological intervention with methylphenidate (MPH) is very common and helpful in the treatment of attention-deficit/ hyperactivity disorder (ADHD). It ameliorates inattention, impulsivity and hyperactivity and improves psychosocial functioning. The core symptoms of ADHD are problematic mainly in demanding structured situations such as in the classroom. It was argued that MPH does not only lead to a decrease of hyperactivity in these situations but may also result in a general dampening of motor activity during non-structured leisure time. Unfortunately, only few clinical trials have investigated this practically important issue and thus it is still a matter of debate. It follows that many parents hesitate to accept psychotropic drugs for their children. To elucidate this problem in the current study, not only overall behavioral ratings (half-day blocks) but also day-long actigraphy was applied during an analogue classroom setting, where structured and non-structured situations alternated over time. Fourty-nine children with ADHD were assessed for treatment effects of once-daily extended-release and twice daily immediate-release methylphenidate (MPH) as well as placebo. Both MPH regimes yielded improved behavioral ratings during morning and afternoon, while actigraphy showed reduced motor activity in structured situations, but not during leisure time. Furthermore, the movement information obtained with actigraphy during structured situations could be differentiated from the one gained with overall behavioral ratings. Thus, while behavioral ratings provide a valid estimate of the overall symptomatology, additional information gathered with actigraphy may help to differentiate the impact of medication on hyperactive movement in different situations during the day. This may reflect a more valid picture of a child's real life and improve the quality of clinical trials. Thus, both methods may be regarded as complementary for the assessment of drug effects in children with ADHD and should be a standard of further laboratory school protocols in clinical trials.