Familial Mediterranean fever (FMF) is the most frequent hereditary inflammatory disease. FMF causes different clinical manifestations in different ethnic groups and countries. In this study, we retrospectively reviewed the records of 1,152 FMF suspected patients (673 female and 479 male) from November 2006 to December 2010. A commercial kit assay for the identification of MEFV (Mediterranean fever) gene mutations based on PCR and reverse-hybridization was used to investigate 12 mutations of the MEFV gene. 52.17% of 1,152 FMF suspected patients had MEFV mutation and 45.25% of them were male. The rate of MEFV mutation among male and female patients were 56.78 and 48.88%, respectively. These results were statistically significant and might support the suggestion that FMF had much more penetrance in male patients (P = 0.009). Not any significant difference was observed between the male and female patients in terms of heterozygote and homozygote mutation carriage rate (P = 0.071). Also not any significant difference was observed between the male and female patients in terms of compound heterozygote mutation carriage rate (P = 0.058).