Idiopathic segmental infarction of the greater omentum is an uncommon cause of acute abdomen. The etiology is still unclear and the symptoms mimic acute appendicitis. Its presentation simultaneously with acute appendicitis is still more infrequent. We present a case of a 47-year old woman without significant previous medical history, admitted with an acute abdomen, in which the clinical diagnosis was acute appendicitis and in whom an infarcted segment of right side of the greater omentum was also found at laparotomy. As the etiology is unknown, we highlighted some of the possible theories, and emphasize the importance of omental infarction even in the presence of acute appendicitis as a coincident intraperitoneal pathological condition.