The sonographic findings in 38 patients with abdominal lymphomas related to acquired immunodeficiency syndrome (AIDS) were reviewed. Thirty-three patients had non-Hodgkin lymphoma, and five had Hodgkin disease. Abnormal masses were detected with sonography in 33 patients (87%). Focal hypoechoic liver lesions up to 10 cm in diameter were visible in 17 patients. Several lesions were anechoic and septated, mimicking fluid. Adenopathy (at the retroperitoneum, mesentery, or porta hepatis) was seen in 15 patients. Other involved areas included bowel, omentum, spleen, kidney, and adrenal gland. AIDS-related abdominal lymphomas frequently cause extranodal masses that can be readily imaged with ultrasound. Ultrasound-guided fine needle aspiration biopsy allows a specific diagnosis to be made in many cases.