Epiploic appendicitis and segmental omentum infarction are considered to be rare conditions, which may mimic an abdominal surgical emergency. The purpose of our study was to describe clinical findings, US and CT appearance of infarction of an epiploic appendage and omentum, and to determine their epidemiological characteristics and natural history. We retrospectively studied clinical, US and CT findings at hospital admission and follow-up of all patients who were diagnosed at our institution with epiploic appendicitis or omentum infarction between June 1988 and November 1997. We found a relatively high incidence of 40 cases: 20 patients with epiploic appendicitis, 11 with omentum infarction, and 9 in whom it was not possible to discriminate between the both. All 40 patients recovered under conservative treatment without complications. We conclude that US and CT features allow a reliable diagnosis, thereby obviating unnecessary surgery. Discriminating between both conditions is of no practical relevance since treatment and prognosis are identical.