Convulsions induced by metrazol have been widely applied in the past few years in the treatment of mental disorders. At first limited to the treatment of schizophrenia, this therapy is now being employed for the affective disorders1and also for severe psychoneuroses.2Von Meduna3in one of his early papers stated that, although the treatment was quite drastic, no inherent danger was involved. Occasional fractures of the long bones and dislocations have been reported.4Recently von Meduna and Friedman B compiled statistics from various sources with regard to the "mechanical" complications, which include dislocations and fractures of the extremities. They did not include the numerous temporomandibular dislocations which undoubtedly occur but which are reduced without difficulty or sequelae. They reported an incidence of 1.1 per cent of such "mechanical" complications. A survey of the literature discloses no reference to vertebral injuries as the result of metrazol therapy except the recent report by Wespi6of a case of fracture of the seventh thoracic vertebra. It is our purpose to report a series of cases of treatment with metrazol in which compression fractures of the thoracic vertebrae were found in a