Acute acalculous cholecystitis (AAC) is a life-threatening condition whose incidence is steadily increasing, although it is still very much lower than that of the corresponding calculus form. The severity of the disease is due to the rapid course towards gallbladder necrosis and biliary peritonitis. Traditionally, it has been thought that AAC is associated with recent trauma, overeating or major surgical procedures. We describe a patient who presented acute cholecystitis, two days after completion of radiation therapy for metastatic lymphadenopathy along the hepatoduodenal ligament and distal common bile duct. He underwent exploratory laparotomy but he died from uncontrolled sepsis three days later. Histological study of the resected gallbladder showed findings of acute acalculous cholecystitis.