THE INCREASING popularity of retroperitoneal insufflation with the increase in adrenal surgery has prompted a review of methods used up to the present time. As shown in the accompanying historical table, it may be seen that in careful hands the procedure carries a very low incidence of reactions but that with variation in the method there seems to be a cycle of increasing usage and increasing complications, eventually with a few fatalities. Accordingly, it is suggested that the utmost caution be used in the performance of the procedure and that it be restricted only to those cases in which no other method of deriving the information is available. It would seem that the communications of the retroperitoneal space are variable from individual to individual and that pressures to fill it adequately cannot be attained without some chance of spread to the mediastinum, scrotum, and subcutaneous spaces. It is essential that