The CT findings of two patients with left-sided omental infarction associated with acute inflammation and abscess formation are described and illustrated. The patients presented with lower abdominal pain, fever, and leukocytosis, and they exhibited a poorly defined heterogeneous low-attenuated mass containing fat in the anterior left lower abdomen. Although segmental omental infarction is usually a self-limiting condition that may resolve spontaneously, necrosis associated with secondary infection and abscess formation may develop occasionally.