As yet, stimulants remain the preferred means of treating attention-deficit/hyperactivity disorder (ADHD) pharmacologically. They are indicated when measures based on behavioural therapy or psychoeducation alone are not sufficient. How-ever, the period of effectiveness of immediate release stimulants is often not satisfactory. A variety of retarded forms of methylphenidate have now been developed and approved for the German market. This paper presents an overview of clinical studies on effectiveness, period of effectiveness and the profile of side effects of different forms stimulants available in Germany. In clinical practice, the new retard products represent effective alternatives. There is an advantage in administering this drug in a once-daily single dose. At the same time, the side effects that are caused by an extended period of effectiveness have to be studied in detail. A more precise adaptation to the daily obligations and needs of children and adolescents is needed. Possibly, a combination with unretareded MPH might lead to a better effect/side-effect profile.