The authors examined 139 patients thought to have early, partial, or intermittent biliary obstruction, using sonography, hepatobiliary scintigraphy, and in selected cases contrast cholangiography. Of 125 patients with a well-established final diagnosis, sonography and scintigraphy disagreed in 29 (23%). Scintigraphy revealed early or low-grade obstruction in 13 patients who had no evidence of dilated ductules, while 7 patients with dilatation from prior stone passage or biliary surgery showed normal clearance. The authors conclude that in a preselected population in whom early or low-grade biliary obstruction may be present, disagreement between sonography and scintigraphy is not rare, and the absence of sonographically detectable dilatation does not exclude obstruction.