A case with multiple liver abscess accompanied by massive portal venous gas is reported. A 61-yr-old male was admitted because of left lower abdominal pain, fever, and diarrhea. Abdominal x-ray examination demonstrated multiple branching lucencies in the liver. Computed tomography revealed multiple liver abscesses and massive gas in the portal system as well as a thickened wall of the sigmoid colon. Enema study using contrast medium revealed a perforation of the sigmoid colon with diverticulitis. The outcome was favorable after sigmoid colectomy in addition to intensive treatment with antibiotics. Bacteroides fragilis, which produces gas (H2 and NH3) by fermentation, was isolated not only from the resected specimen but also from blood samples. Although the presence of portal venous gas is a sign of poor prognosis in patients with intestinal infectious diseases, the sensitive detection of hepatic portal venous gas by computed tomography and the appropriate treatment may improve the patient's prognosis.