Ankylosing spondylitis (AS) is a common inflammatory rheumatic disease. Mediterranean fever (MEFV) gene, which has already been identified as being responsible for familial Mediterranean fever (FMF), is also a suspicious gene for AS because of the clinical association of these two diseases. The aim of this study was to explore the frequency and clinical significance of MEFV gene mutations (M694V, M680I, V726A, E148Q and P369S) in a cohort of Turkish patients with AS. Genomic DNAs of 103 AS patients and 120 controls were isolated and genotyped using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods. There was a statistically significant difference of the MEFV gene mutation carrier rates between AS patients and healthy controls (p=0.004, OR: 2.5, 95% CI: 1.32-4.76). This association was also observed in allele frequencies (p=0.005, OR: 2.3, 95% CI: 1.27-4.2). A relatively higher frequency was observed for M694V mutation in AS patients than controls (10.7% versus 4.2% , p=0.060). There were no significant differences between MEFV mutation carriers and non-carriers with respect to the clinical and demographic characteristics. The results of this study suggest that MEFV gene mutations are positively associated with a predisposition to develop AS.