Ankylosing spondylitis (AS) is chronic, progressive, systemic inflammatory rheumatic diseases that lead to serious disability. The objective of this study was to determine the demographic, clinic characteristics and CYP2D6*4 gene mutation profiles of the AS patients in Tokat, Turkey. In this retrospective study, we evaluated 103 patients that were diagnosed and followed up as AS in Tokat, Turkey between 2008-2011. Demographical properties (age, sex, education level, age at diagnosis, disease duration), clinical characteristics (HLA27, peripheral/extraarticular involvoment, chest expansion, enthesopathy, modified schouber) and genetic analysis results (CYP2D6*4 gene mutation frequency) of AS patients were assessed. The mean age of AS patients was 36.80±9.25 years. The mean age of female and male 39.10±7.89, 35.40± 9.79 respectively. The female to male ratio was 1:1.6. Major histocompatibility complex, class I, B 27 (HLAB27) was investigated and the rate of positivity was 73.78 %. There was a statistically significant difference between CYP2D6 gene mutation and peripheral /extraarticular involvement (p<0.05). Determining the clinical characteristics and CYP2D6*4 gene mutations of rheumatologic diseases as AS will provide benefits for early diagnosis, treatment, and disease outcome.