An adult female domestic crossbred rabbit was referred to Small Animal Hospital, faculty of veterinary Medicine, University of Tehran with a history of anorexia and inability to gain weight on hind limbs. Clinical examination revealed listlessness, lethargy, distention of the abdomen and grinding of teeth. Haematological and Serum biochemical examinations were normal except a mild hypocalcemia. In radiology a mild depression in bone density and six fetuses were detected. Fetuses were dead according to sonographic evaluation, course they did not have any heart beats. There were no other abnormality in radiology of other organs including teeth, abdomen, pelvic cavity and vertebrates. In spite of administration of fluids and calcium, unfortunately the animal died. At necropsy, cyanosis of mucosa, severe congestion of carcass and viscera, ulceration of gastric mucosa were present. The liver had nut meg appearance and the gall bladder was distended. Petechial hemorrhages were present at beneath of visceral pleura and the lungs were congested and edematose. Klebsiella pneumonia were isolated from visceral organs and the bone marrow. Histopathologic examination revealed severe edema, hemorrhages and lymphocytolysis in the lymph nodes. A foci of fatty changes and hemorrhages were observed in the liver. Congestion, sludging and microthrombi were observed in the brain capillaries. Acute alveolar edema was presented in the lungs. Other organs were congested. On the basis of mentioned findings, the cause of death in this animal was septicemia due to fulminate infection ofK pneumonaie.