Aspects of indoieamines relevant to schizophrenia are: (a) the psychotomimetic actions of indoleamine-related psychedelic drugs, and (b) the existence of enzymes capable 01”methylating indoleamines to form psychedelic drugs in the human body. The existence of psychedelic drug psychosis and the fact that drugs such as mescaline and dimethyltryptamine resemble catecholamines and indoleamines respectively prompted the speculation that the brains of schizophrenics might methylate normally occurring amines to form psychotomimetic agents which account for schizophrenic symptoms.