The human leukocyte antigen HLA-B*27 is a Class 1 antigen of the major histocompatibility complex (MHC) with B locus and has been established in association with pathogenesis of Ankylosing Spondylitis (AS) since 1973. AS is a multifactorial disease which occurs due to interaction between genes, environment, mechanical stress, microbiota and infection. The ankylosing spondylitis is characterized by inflammation of spine, backpain, stiffness of lower back and hips, extrarticular organs such as eyes, and cardiovascular system. In severe cases this may cause the fusion of vertebrae. The current study highlights the mechanism involved in the pathogenesis of AS with a focus to investigate the frequency of HLA B*27 in suspected cases of AS. The patients were recruited from rheumatology clinics of India from age group of 13-69 years. Patients with suspected cases of AS who met the clinical criteria for AS were tested for HLA-B*27. One thousands and four patients were tested for HLA B*27 using RTPCR method. Out of 1004 subjects, 124 (12.35%) were positive for HLA-B*27. Among these, Male/Female ratio was 2.7. Majority of subjects were from North India. The current study highlights the HLA B27 positivity in association with pathogenesis of AS and indicates that HLA B27 serves as a rapid prognostic and diagnostic genetic marker for detection of AS.