A male student, 22 years old: Family history: He has a sister with mental weakness. Symptoms: Schizophrenia of 2 years' duration. He was treated with electric and insulin shocks, and with chlorpromazine and reserpin without avail. The administraticn of perphenazine (PZC) at last alleviated his symptoms. However, he had relapse three months later, and became so despondent of life that he took 260 mg PZC in one dose with an intention to commit suicide. This induced a deep sleep, followed by trismus and with a slight salivation, but no danger to his life. Such a large dose of PZC had no favorable effect on his symptoms. Yet, this patient improved soon afterward by daily administration of 12 mg PZC continuously. In this one I have been able to recognize that PZC has a little side-effect and there is no great danger to life in its administration, as contented by many investigators.