Brucellosis is still a public health problem, particularly in developing countries. After the primary infection subsides, a chronic stage characterized by nonspecific manifestations can develop, during which it may not be possible to isolate Brucella organisms and agglutination test titers may or may not be high. We present the case of a 49-year-old man who had only nonspecific symptoms and a 2-month history of a pulsatile painful swelling in his right popliteal region. He had no history of trauma or surgery in that region, but he did ingest unpasteurized milk products. The patient's agglutination test titers were high, and Brucella melitensis was isolated from a bone marrow culture. Color Doppler sonography, T2-weighted MRI, and digital subtraction angiography were performed. Treatment with ultrasound-guided compression of the pseudoaneurysm failed because of high blood flow in its neck. Aneurysmectomy was undertaken, and the excised material was consistent with that from a mycotic pseudoaneurysm. Although both MRI and angiography provided useful information, the color Doppler sonography findings were characteristic of a pseudoaneurysm in the popliteal artery, and only that modality could detect the flow dynamics within the pseudoaneurysm. (C) 2003 Wiley Periodicals, Inc.