IN THIS REPORT, the course of manic-depressive psychosis is compared in two groups of patients, one treated with electric shock and the other, a control, not so treated. After discharge, both groups were followed in order to evaluate the more permanent effects of shock therapy. In addition, an analysis is presented of certain factors which the literature indicates may be related to the course of the psychosis. These factors are: family history, prepsychotic personality, age of onset, acuteness of onset, type of onset, severity of illness, typicality of depression, number of previous depressions, duration of illness before treatment, number of shocks and sex of the patient. In this paper, "manic-depressive psychosis" refers to a psychosis in which the primary psychopathology is in the affect. The subtype "depressive" is defined as depression of spirits with psychic and motor retardation. Such depressions are classified as typical. Depressions with agitation, paranoid features, perplexity