The study was finished according to schedule with 32 of the 49 examined patients, i.e. without changes in neuroleptic medication. The antiparkinson medication had been suddenly withdrawn in all patients. No patient had to be given another antiparkinson treatment due to reappearing Parkinson symptoms. Slight and constant deterioration in their condition occurred in four patients within 1-3 weeks following withdrawal of the antiparkinson medication; this fact justified recommencement of the antiparkinson therapy. All but seven patients had been given antiparkinson drugs for more than 1 year. All patients were on neuroleptic drugs. The neuroleptic dose was increased in seven patients, a slight transient deterioration of the Parkinson symptoms occurring in two cases. Investigation into the longitudinal course of the diseases revealed that the intensity of symptoms is not always steady, but that certain variations occur. An equable course was observed in paranoid schizophrenics. In cases of catatonia and hebephrenia variations in the symptoms and their intensity must be expected. However, these variations need not inevitably call for recommencement of the antiparkinson treatment. Thus, our results confirm similar available studies in that the incidence of relapses in cases of neuroleptically conditioned Parkinson's disease is very low in patients who had been receiving antiparkinson medication for long periods; this incidence of relapses amounts to 8% in our study. Our figures are lower than those referred to in literature up to now. Within 1-3 weeks following withdrawal it becomes obvious whether another antiparkinson therapy will be necessary or not. Within the scope of our study, we cannot comment on the statement that antiparkinson drugs may be withdrawn, without any risk of a relapse, after 3-month administration.