A 29-year-old woman was referred for abdominal pain. Results of tests for lupus anticoagulant and antibodies to phosphatidylserine and to β2-glycoprotein I were positive, but the patient had no features of systemic lupus erythematosus (SLE). Abdominal ultrasonography showed a thickening of the gallbladder wall without cholelithiasis. A surgical procedure revealed necrotic areas of the gallbladder wall, and a cholecystectomy was performed. Histologic examination of the gallbladder showed multiple thrombi and no vasculitis. Despite full-dose heparin, the patient developed a catastrophic antiphospholipid syndrome (APS) and subsequently died. Among connective tissue disorders, acute acalculous cholecystitis has been reported in patients with polyarteritis nodosa and/or SLE. APS should be considered as a possible cause of acalculous cholecystitis.