Gallbladder volvulus is an unusual cause of acute abdomen. After the first case published by Wendel, about 500 cases have been documented in the medical literature.This condition is defined as torsion of the gallbladder around its artery and duct in case of long and flask mesentery. The one presented here is a case of a 85 year-old woman who complained of right subcostal pain since 48 hours without fever. The echography revealed a large thick-walled gallbladder with a common bile duct diameter of 10mm without stones. Laparotomy through a right subcostal incision revealed a serohemorrhagic exudate with complete torsion of the gallbladder which was ischemic and gangrenous without perforation. Cholecysectomy was performed with a cholangiography which was normal. The anatomopathologic examination confirmed the diagnosis of acute gangrenous cholecystitis. Gallbladder volvulus is a nonfrequent cause of acute cholecystitis.