[Methylphenidate addiction--Reversal of effect on withdrawal]

A case history of a prolonged ritalin addiction (18 years) is given, describing the symptoms and the diagnostic categorisation. Because of the remarkable, somewhat atypical withdrawal symptoms, it is suggested to conceive these withdrawal symptoms as an expression of a 'reversal of effect on withdrawal' in the sense of a continuing, independent manifestation of counter regulatory, protective and specific mechanisms.