Endoscopy versus x-ray studies of the gastrointestinal tract: future health care implications. I did esophagogastroduodenoscopy in 147 patients and colonoscopy in 59 patients who had had gastrointestinal x-ray studies. The endoscopic procedure was done within 7 days after the x-ray study and/or while the patient was still symptomatic. The barium swallow findings were confirmed in only 40%; in the other 60%, the x-ray findings could not be confirmed. These unconfirmed x-ray findings were false-positive in 37.4%, false-negative in 16.3%, and suboptimal or nondiagnostic in 6.2%. The barium enema findings were confirmed in 32%. In the other 68%, the x-ray findings were false-positive in 42.3%, false-negative in 22%, and suboptimal in 3.3%. We conclude that in clinical or private practice, relying on x-ray studies alone may be associated with a high margin of diagnostic errors. When all factors are considered, the initial cost advantage of the x-ray studies appears to be lost. In future recommendations on the continuing dilemma of x-ray studies versus endoscopy, consideration should be given to factors other than the initial lower price of the x-ray studies. 