Mirizzi syndrome (MS) represents an uncommon clinical condition, being characterized by a narrowing of the common hepatic duct or its erosion by stones impacted in the cystic duct or gallbladder Hartman's pouch. Very uncommonly, MS can be reported in patients with contemporaneous bile duct anomalies. The case is reported of a 76-year-old Caucasian woman with a MS with a cholecystobiliary fistula and a contemporaneous aberrant biliary duct for the right posterior segments.Due to the presence of an anatomical abnormality, an open approach was decided: also during surgery, it was impossible to clarify which part of the biliary tree the accessory duct merged into. After surgery, post-operative course was uneventful: the patient is alive without medical problems (follow-up: 16 months). MS represents a challenge for the surgeon. Contemporaneous presence of biliary abnormalities is anecdotic, increasing the risk of iatrogenic injuries. An open approach may be preferred in these conditions.