A study was conducted on 66 psychiatric inpatients who took major tranquilizers for periods of four to 16 years. The frequency of signs of Parkinsonism and the effects of orphenadrine on these were studied in a double-blind crossover method. Sixty-one per cent of the patients showed signs of Parkinsonism. Female patients and those with organic brain pathology more frequently exhibited Parkinsonism (although the difference was not statistically significant). No correlation was found between duration of treatment and extrapyramidal effects. Of the 40 patients who developed Parkinsonism, 25 responded favourably to orphenadrine, while six (15%) had more marked manifestations on orphenadrine than on placebo.