AIM OF THE STUDY: There are several varieties of bilioenteric fistulae. The vast majority of fistulas result from chronic cholelitiasis disease. Other relatevely common causes are chronic duodenal ulcer disease, previous instrumentation to the biliary system, chronic bowel inflammatory disease, traumatism, infections. CASE REPORT: The case of a 58-year-old patient is reported in whom one of the rare complications of longstanding duodenal ulcer, the cholecystoduodenal fistula, has occurred. Main symptoms were rapid weight loss (20 kg/3 months), abdominal pain, dyspepsia, vomiting. Perivisceral peritonitis developed a tumefaction (diam: 5 cm) involving duodenum, pancreas, biliary tract and gallbladder. That finding closely simulated a neoplasm evaluating it by CT scan, US scan and even in explorative laparotomy: tumefaction was impossible to isolate, so a duodenocefalopancreasectomy was performed.