Background and Study Aims: Choledochocele (CDCL) is still regarded as being a rare abnormality, despite the increasing number of case reports published in the last ten years. The aim of this prospective study was to investigate the prevalence rate of CDCL in patients referred for endoscopic retrograde cholangiopancreatography (ERCP), as well as the short-term and long-term complications of endoscopic treatment., Patients and Methods: Over a seven-year period, fifteen symptomatic patients (ten male, five female, age range 47-93 years) were identified as having CDCL out of a total of 1019 ERCP referrals to our unit. The diagnosis of CDCL was made by both duodenoscopy and ERCP., Results: All 15 patients had small (4-25 mm) CDCLs associated with pancreatic (n = 1) or biliary (n = 14) disorders. Ten of the 15 patients (67%) had choledocholithiasis as well. Twelve patients were treated by endoscopic sphincterotomy (ES), and three by surgery. The immediate post-ES complications (2 of 12, 16.7%) were acute cholangitis (n = 1) and acute pancreatitis (n = 1). Eleven (76%) of the 14 patients who had a complete follow-up were symptom-free, with normal liver function tests at a median of 18 months (range 12-97). Two patients reported episodes of acute cholangitis, and one patient died of a misdiagnosed ampullary carcinoma arising in the CDCL., Conclusions: These results suggest that CDCL is probably an overlooked diagnosis in patients with pancreaticobiliary symptoms. It should be readily recognized and treated, preferably by endoscopic sphincterotomy. The endoscopist must be aware that an ampullary carcinoma may develop in a CDCL.