Thirty-eight patients with calcific cholecystolithiasis underwent extracorporeal shock wave lithotripsy (ESWL) of the gallbladder on an outpatient basis. Twenty-two (60%) patients had fragments smaller than 3 mm on follow-up ultrasound (US) studies after an average of 13,450 shock waves and four lithotripsy sessions. Nineteen of these 22 patients were followed up for an average of 18 weeks, and only three were found to be free of residual fragments at US. The other three patients were lost to follow-up. Sixteen patients are still undergoing biliary ESWL. Comparison of calcified and noncalcified gallbladder calculi revealed that calcified stones required 50% more shock waves for successful fragmentation, fragments cleared considerably more slowly from the gallbladder, and patients had a higher frequency of acute pancreatitis (5% vs 2%) and transient hematuria (8% vs 3%). Stones with dense homogeneous calcification required significantly fewer shock waves for successful fragmentation than stones with calcific lamination. ESWL can be applied occasionally in patients with calcific cholecystolithiasis if an alternative to surgery is required, but success has been limited.