Stimulants are the matter of choice to treat attention deficit/hyperactivity disorder (ADHD) pharmacologically. The period of effectiveness of immediate release stimulants is, however, often not satisfying. Currently a variety of retarded forms of methylphenidate and also amphetamine were developed in order to minimize the problems involved in a daily dose. This paper presents the clinical studies on effectiveness, period of effectiveness and the profile of side effects of different forms of stimulants. In the clinical practice the new retard products are effective alternatives. There is an advantage in giving this drug in a once daily single dose. At the same time, the side effects that are caused by an extended period of being effective have to be studied in detail. A more exact adaptation to the requirements of daily obligations and needs of children and adolescents is difficult to realize. Future research is supposed to test schemes of titration including immediate and sustained released stimulants.