The physiological correlate of biliary colic is a rapid increase in pressure in the presence of biliary obstruction. The relaxing action of hymecromone on the biliary tract provides a pharmacotherapeutic approach. As the symptoms usually occur postprandially we used ultrasonography to examine whether hymecromone was able to reverse the contraction of the common bile duct (CBD) after ingestion of a standardized test meal. The study was designed as prospective, double-blind randomized crossover study versus placebo in 20 healthy volunteers. The width of the CBD was measured ultrasonographically in the fasting subjects and at 1, 3, 5, 10, 15 and 20 minutes after ingestion of a test meal. Then the subjects were given either 400 mg of hymecromone or placebo and the measurement series was repeated. After ingestion of the test meal the width of the CBD decreased by a maximum of 20% after 15 minutes. While there was only a slight increase in the width of the CBD after subsequent administration of placebo, a maximum increase of 36% was measured 10 minutes after administration of hymecromone. The postprandial contraction of the CBD can be reversed within a short time by iv administration of hymecromone.