Background: Ankylosing spondylitis (AS) is an inflammatory disease that mainly affects axial skeleton of the body and ankylosing spondylitis ligaments around the spine at the junction of the spine are inflamed, because the disease is progressive and can lead to significantly cause of disability and the studies could provide a mechanism for the early detection of the disease or help determine when to start treatment, the difference in clinical presentations of AS in men and women is indicative of potential effect of gender on severity of the disease. This study was conducted with the aim to investigate the effect of gender on severity of AS. Methods: In a cross-sectional study, one hundred and fifteen patients with ankylosing spondylitis who referred to Yazd Rheumatology Clinic between 2001 and 2013 were evaluated. Sampling was performed using non-random convenient method. The most important variables studied included demographic data, clinical presentation, radiographic stage of sacroiliac involvement, and laboratory data extracted from patients’ files and recorded in questionnaires. Results: Both groups according to age at diagnosis, presence of enteritis, peripheral joint involvement and laboratory data such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and hemoglobin were matched. Inflammatory neck pain was more prevalent in men than in women (77.2% against 51.8%; P< 0.05). Sacroiliac radiographic study revealed stage 1 involvement in 11.3% of men and 37% of women (P= 0.009), and stage 4 in 27.2% of men and 3.7% of women (P< 0.001), with a significant difference. Conclusion: According to the results of the study, the time between age of onset and age at diagnosis, inflammatory pain in the neck and advanced stage in men than in women was higher. Although these findings suggest that gender may have an impact on the pattern and severity of AS but the time delay in diagnosis as a disease affecting the intensity and pattern should not be overlooked.