The aim of this study is to present the abdominal CT findings of patients with familial Mediterranean fever (FMF) examined during an acute abdominal attack. CT scans of 17 patients (10 women and 7 men; age range 11-45 years) were retrospectively reviewed. Attention was directed to mesenteric or peritoneal abnormalities and to the presence of appendiceal pathology. Patients were divided into two groups; group A (n=14) consisted of patients with an acute abdominal attack caused by FMF, and group B (n=3) consisted of patients whose attack proved to be owing to a separate pathology requiring surgery. Characteristic CT findings of acute abdomen in FMF included mesenteric pathology (n=12), mainly of engorged vessels with thickened mesenteric folds, mesenteric lymphadenopathy (n=6) and ascites (n=6). Signs of focal peritonitis were found in four patients. Radiologists should be familiar with such CT findings of peritoneal irritation in patients with FMF during an acute attack, and may suggest this clinical diagnosis in the proper clinical setting in a patient who has not been previously diagnosed. Alternatively, the radiologist should be aware of the possibility of a concurrent acute appendicitis or other acute abdominal pathology in patients with known FMF and should search for it.