We proposed that clinical criteria could define a group of patients very unlikely to have abnormal preoperative chest roentgenograms. Nine hundred five surgical admissions were screened for the presence of clinical factors we thought would make those patients more likely to have abnormal preoperative chest roentgenograms. Of these, 368 had no risk factors. One patient (0.3%) of the 368 had an abnormal x-ray film, which did not affect the surgery. No material abnormalities were found in the remainder of the group without risk factors. Five hundred four patients had identifiable risk factors. Of these, 114 (22%) were found to have serious abnormalities on preoperative chest roentgenogram.