ESWL will be performed in all patients using a electromagnetic lithotriptor as previously described. Shock-waves will be focused on the obstructing stones (if multiple stones are present, those responsible for MPD obstruction will be identified by comparing plain abdominal film, CT Scan and S-MRCP). ESWL sessions will be repeated if necessary, until stone fragmentation is obtained, as confirmed by abdominal plain film centered on the targeted area of the pancreas. At this time, treatment will be considered terminated in the ESWL group, patients in the endoscopy group will undergo endoscopy immediately, for endoscopic extraction of stone fragments possibly associated to stent insertion according to previously published criteria and techniques.