Radionuclide esophageal transit study (RETS) has been developed to assess motor function of the esophagus. The purpose of this study was to compare RETS to esophageal motility studies (EMS) in detection of motility disorders. A total of 109 consecutive patients without previous history of surgery on the esophagus underwent both RETS and EMS within one month of each other. Final diagnosis was divided into three categories: I--primary esophageal motor disorders (n = 39); II--reflux disease (n = 48); and III--non-cardiac chest pain and/or dysphagia (n = 22). Using EMS as the standard, the results of RETS were as follows: sensitivity for detection of motor dysfunction was 97%, 92%, and 77% for Groups I, II, and III, respectively, while specificity was 91% for Group II and 100% for Group III. Global sensitivity was 92% and specificity was 88%. No clinically significant motor disorders were missed by RETS. In conclusion, RETS is a useful noninvasive test for the screening of patients with symptoms thought to be of esophageal origin.