Sixteen patients, 7 women and 9 men, with a mean age of 42 years and with recurrent attacks of abdominal pain as a result of chronic calcifying pancreatitis, were treated with extracorporeal shock wave lithotripsy (ESWL), after endoscopical removal of one or more stones from the main pancreatic duct had proved impossible. In all patients fragmentation by ESWL of the stone situated farthest distally was attempted, after which the remaining calculi and fragments could be voided spontaneously or could be flushed via a drain placed endoscopically in the main pancreatic duct. In 12 patients (75%) fragmentation of stones was achieved, 11 of them had a dramatic relief of pain immediately after ESWL. In 7 patients (44%) stone clearance was achieved; at follow-up (1-38 months after ESWL) none of these had complaints. Of the 5 patients with stone fragmentation without stone clearance, 2 were operated on because of recurrent symptoms. The only complication seen after ESWL, was an exacerbation of pancreatitis in 1 patient, which could be treated conservatively. If pancreatic stones cannot be removed endoscopically, ESWL appears to be an attractive alternative to an operation. It is important to achieve stone clearance.