The retained stone in the common bile duct remains a problem for the surgeon. Although more effective methods are available, mechanical flushing of the bile duct is, when successful, a simple solution. Pharmacological dilatation of the sphincter of Oddi is a logical adjunct to flushing. Pressure changes in the bile duct during flushing were studied in 20 postoperative patients with T‐tube drains and the effectiveness of two drugs in reducing Omnopon induced spasm of the sphincter was compared. Hymecromone intravenously and lignocaine via the T‐tube were equally effective, reducing sphincter activity in the majority of patients, but there was considerable individual variation.