1. Comparing films of the spine taken before and after treatment in a series of 200 metrazol-treated cases, a fracture incidence of 23 per cent was found.2. Fractures were found more frequently in males (28.6 per cent) than in females (19 per cent).3. The incidence of fractures is much greater in patients over 55 years of age and under 21. In the former group, we believe this is due to the relative osteoporosis present in the spine, while the fact that the spines in the young age group have not attained their full adult strength is a contributing factor to the increase in injury in this class.4. The mental condition present and its duration show no relationship to the incidence of fracture in these patients.5. Metrazol does not appear to affect the calcium metabolism in the body.6. In the 46 cases, 111 vertebral bodies were fractured, i. e., 2.4 per patient. No other parts of the vertebrae were involved, and no dislocations occurred. This would explain the absence of spinal cord involvement.7. All the fractures occurred in the dorsal spine, the fourth, fifth and sixth being the most frequently injured.8. Multiple fractures occurred more often in males than in females, due, in our opinion, to the greater muscular development of the former and the more powerful convulsions produced in them.9. In agreement with other published reports, we have found that the symptoms produced are much milder than would be expected from examination of the radiographs of the injured spines.10. We strongly recommend that routine pre-treatment lateral radiographic examinations of the thoracic spine should be done to determine the presence of any contra-indications, and to discover any irregularities in the appearance of the vertebræ which might simulate minor injuries and thus confuse the issue when post-treatment films are examined. All cases should be x-rayed after treatment to diagnose symptomatic and asymptomatic fractures.11. Kyphosis, scoliosis, arthritis, nuclear change and old fractures are no contra-indication to metrazol therapy. Osteoporosis appears to be a contra-indication.