• Ethopropazine was used in treating 147 patients with paralysis agitans. The cases were almost equally distributed among the postencephalitic, the idiopathic, and the arteriosclerotic types, and all patients were chosen because their symptoms of rigidity and tremor had failed to respond to other drugs. Against the more severe kinds of tremor, ethopropazine was more effective than any other drug in current use. Most patients slept better and improved in gait, station, posture, and speech. The doses used commonly caused drowsiness and dizziness, but no serious side-effects were observed. Close attention to dosage was necessary.