The method to be described for the visualization of retroperitoneal tumors is neither original nor new but is presented because I feel that it is not receiving the attention which it merits. Insufflation of a gas into the perirenal space was first used for the visualization of the soft parts of the region by subsequent roentgenograms by Carelli1in 1921. Quinby2used the method in 1923, Cahill3described his modification in 1935 and reported again on its use in 1936, and a report by Mencher4appeared in 1937. Aside from these references, however, little has appeared in the American literature. The procedure is not one to be adopted as a routine, but in view of the current interest in tumors and hyperplasias of the adrenal glands it deserves emphasis as an important special method for the diagnosis of such lesions. Adrenal tumors have occasionally been demonstrated