In 853 clinical examinations, the authors compared three cholecystographic agents: Bilopaque (tyropanoate sodium), Oragrafin (ipodate sodium), and Telepaque (iopanoic acid). Iopanoic acid tended to produce the densest gallbladder shadows and the highest frequency of stone demonstration, common duct opacification, side effects (diarrhea and dysuria), and the lowest incidence of double-absent shadows. With ipodate sodium the frequency of dim and absent shadows was greatest, and that of common duct opacification, stone demonstration, and side effects the least. Results with tyropanoate sodium were intermediate. Pathologic correlation failed to demonstrate superiority of any one contrast agent.