PURPOSE: To evaluate abdominal computed tomographic (CT) findings in patients with human immunodeficiency virus (HIV) infection. MATERIALS AND METHODS: CT scans with abnormal findings in 259 patients (247 men, 12 women; age range, 21-60 years) with HIV infection were analyzed. Diagnoses were mycobacterial infection (n = 87), lymphoproliferative disease (n = 63), Kaposi sarcoma (n = 17), fungal infection (n = 17), hepatocellular disease (n = 13), Pneumocystis carinii infection (n = 8), other disorders (n = 39), or unknown (n = 30). RESULTS: Abnormal findings included lymph-node enlargement (n = 159), hepatomegaly (n = 100), splenomegaly (n = 62), gastrointestinal mass or wall thickening (n = 61), and low-attenuation lesions in the liver (n = 50) or spleen (n = 55). Diagnoses thought to account for CT findings were made (n = 229) or suspected (n = 18) in 247 (95%) of the 259 patients. CONCLUSION: In most patients with HIV infection, abnormal abdominal CT findings are due to a second disease. Even relatively nonspecific findings should not be ascribed to HIV infection and should prompt a search for an opportunistic infection or neoplasm.