In 1948, Mirizzi described a syndrome characterized as the obstruction of the common hepatic duct by a stone located in the gallbladder's neck or in the cystic duct. We present a rare case of Mirizzi syndrome resulting from a fistula involving the cystic duct, the neck of the gallbladder, and the right hepatic duct. This finding was possible because the patient had a rare biliary anatomic variation: the insertion of the cystic duct straight in the right hepatic duct. The diagnosis was suggested by abdominal ultrasonography and confirmed by endoscopic retrograde cholangiopancreatography. The surgical approach was performed by means of an open cholecystectomy, common biliary duct exploration using the right hepatic duct and a transduodenal papillotomy, and insertion of a long limb T-tube through the right hepatic duct to drain the common duct. The procedure was successful, and after an 18-month period, the patient is free of symptoms.