Complete surgical removal of staghorn or multiple renal calculi is extremely difficult. Intraoperative roentgenography has been used to decrease the incidence of residual calculi. We herein assess the effectiveness of intraoperative roentgenography and emphasize important operative technical aspects. Between 1973 and 1979, 42 patients underwent 50 operations for the removal of staghorn or multiple renal calculi. Intraoperative roentgenography was used in 47 operations and omitted in 3. Of the 47 operations done with intraoperative roentgenography 31 units were free of stones and 12 had small retained fragments known intraoperatively with verification by postoperative tomography or plain abdominal film. In 1 case of calculus recognized intraoperatively passed during the postoperative period and tomograms demonstrated no residual calculi. Only 3 patients had residual stones postoperatively with negative intraoperative films. The 3 patients who did not have intraoperative roentgenography all had residual fragments. All 3 kidneys were thought to be free of residual stones as determined by visual inspection and nephroscopy. With the aid of intraoperative roentgenography the incidence of residual stones was 23 per cent. Followup for up to 6 years in 45 renal units showed 73 per cent to be free of stones. When properly used intraoperative roentgenography is highly accurate. Films should be obtained before any stones are removed and care should be taken to x-ray the entire kidney even if 2 films are required. Final films should be obtained after all fragments are removed.