Familial mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent and self-limiting fever, peritonitis, arthritis, synovitis, pleuritis, carditis, and erysipelas-like lesions. The aim of this study was to investigate the frequency of the MEFV gene mutation in patients who admitted to hospital with preliminary diagnosis FMF and who had undergone a prior appendectomy.We retrospectively reviewed the files of 52 patients between the ages of 7-18 who admitted to hospital with preliminary diagnosis of FMF and who had undergone a prior appendectomy. Age, gender and the MEFV gene mutations were included in the data. The 12 known, common MEFV gene mutations [E148Q, P369S, F479L, M6801 (G/C), M6801 (G/A), 1692del, M694V, M6941, K695R, V726A, A744S, R761H] were investigated in the patients.Of these 52 cases, 29 (55.8%) were female and 23 (44.2%) were male. Their mean age was 12.1 +/- 3.1 years (range 7-18 yr). MEFV gene mutation was detected in 31/52 cases (59.6%). In this study was found an high frequency of the MEFV gene mutation in patients admitted to hospital with a preliminary diagnosis FMF who had undergone a prior appendectomy. MEFV gene mutations were M694V 16/41 (39%), E148Q 13/41 (31%), M6801 6/41 (15%), V726A 4/41 (10%) and R761H 2/41 (5%). Other genes mutations were F479L, M6801 (G/A), 1692del, M6941, K695R and A744S.There are too much indications of unnecessary appendectomy in MEFV gene mutation carriers. In MEFV gene mutation carriers the frequency of appendicitis can be higher than the normal population. A more detailed and extensive study should be done about it.