The trial involved 69 female, long-stay inpatients of the Voorburg mental hospital, of a median age of 50 years. Two groups were formed at the start of the trial. The first group (51 patients) on a maintenance therapy with orphenadrine, were now put on oral dexetimide. Individually adapted dosages ranged from 0.5 to 1.5 mg daily. The control group (18 patients) of antiparkinsonian agents did not take any in the course of the study either. After three and six months (end of trial) biochemical and haematologic parameters were assessed. Clinical evaluation of extrapyramidal symptoms was made in the dexetimide group. All patients of the control group and 47 of the dexetimide group completed the trial. Both groups were shown to be comparable with regard to all parameters. Statistical analysis showed significant improvement in dexetimide-patients with regard to gross motor tremor, facial inexpressiveness, parkinsonian gait (after two weeks) + dyskinesia (after six months).