Radionuclide measurement of esophageal transit has been proposed as a screening test for esophageal motor dysfunction. In this study we evaluated the radionuclide esophageal transit test in 49 consecutive patients undergoing esophageal manometry for esophageal motor disorders. Esophageal transit was assessed using a 10-ml water bolus labeled with 250 microCi technetium-99m sulfur colloid. In preliminary studies in 14 healthy controls, mean transit time was 9.6 +/- 2.1 (SD) sec. Prolonged transit (greater than 15 sec) was observed in two of 28 swallow sequences in the control subjects. Transit times were prolonged in all patients with achalasia or diffuse esophageal spasm, and in five of seven patients with nonspecific abnormalities of peristaltic progression. The test was abnormal in only three of seven patients with high-amplitude peristalsis (nutcracker esophagus) and in none of three patients with hypertensive lower esophageal sphincter. Additionally, prolonged transit was seen in two of 18 patients with normal manometry. We conclude that the radionuclide transit test using a liquid bolus successfully identifies motor disorders characterized by defective peristaltic progression but not disorders in which peristalsis is intact. A major limiting factor appears to be the small number of swallow sequences tested. The test may not, therefore, be accurate enough to consider adopting as a sensitive and noninvasive screening test in the evaluation of patients with suspected esophageal motor disorders.