During the past few years, a number of new compounds have been developed for the radiographic visualization of the gallbladder. By and large, these materials have been designed not only to provide greater opacification of that organ than their predecessors but also to reduce the number and severity of the clinical reactions which frequently follow the administration of gallbladder dyes. Some of these compounds, such as iodoalphionic acid (priodax), have proved quite satisfactory and are now widely used throughout this country. Recently, a new gallbladder compound has been developed2 and has been made available in limited quantities for experimental purposes. This material, to be marketed under the name of telepaque, contains approximately 67 per cent iodine by weight. Like iodoalphionic acid, it has been prepared for oral administration. The currently recommended dose has been established at a level of 3 gm. Clinical Study In preliminary trials at the Johns Hopkins Hospital, telepaque produced sufficiently better results than those obtained with other gallbladder media that an investigation was undertaken to evaluate the characteristics of the compound on a quantitative basis. In this study, telepaque (3 gm.) and iodoalphionic acid (3 gm.) were administered alternately to 200 more or less consecutive patients who were referred to the Department of Radiology for gallbladder examination ; that is, 100 patients received one compound and 100 patients the other. The group who received iodoalphionic acid served as a standard of reference in the evaluation of the newer drug. In each of the 200 patients, the gallbladder medium was administered after a light fat-free dinner during the evening preceding the day of the examination. The films were obtained during the morning hours, approximately fifteen hours after the administration of the compound. The patients who received telepaque were similar in most respects to those who received iodoalphionic acid. The age and sex distributions, as set forth in Table I, show no great differences. In both instances, females predominated over males and the age groups of forty to fifty-nine years had the greatest representation. Forty-rive of the patients who received telepaque had had previous episodes of gallbladder colic; 43 of those taking iodoalphionic acid gave a similar history. Of the patients who received telepaque, 69 complained of eructation; 68 of the patients taking iodoalphionic acid presented this complaint. Fat intolerance was experienced by 67 of the patients who received telepaque; of the patients taking iodoalphionic acid, however, only 48 had this experience. In view of these data, it is evident that the individuals who took telepaque presented characteristics which were closely similar to those of the patients who received iodoalphionic acid.