Ankylosing spondylitis (AS) is a complex and debilitating diseasecharacterized by axial ankylosis, inflammation at the insertion of tendons,and occasionally, peripheral arthritis. The advent of biological therapy in the last several years, with agents that specifically inhibit cytokine pathways,such as tumor necrosis factor alpha (TNF-α) antagonists, has fundamentallyaltered the clinical approach to the spondyloarthropathies. Our study aimedto analyze the effect of these biological agents on our AS patients.(Manadan et al., 2007). To evaluate the efficacy of TNF alpha blocking therapy on ASaccording to the validated composite measure, international Assessment ofSpondyloArthritis international Society ASAS (formerly Assessment inAnkylosing Spondylitis) response criteria (pain, patient global assessment,function, and inflammation). A comparison between the two TNF alphablockers used in our study was done (etanercept and infliximab) to testsuperiority of any of these agents to the other. Twenty five AS patients with mean age of 36 years (36.04 + 11.97years) and mean disease duration of 10.64 + 6.6 years were included in thisstudy. The patients were divided into three groups according to the antiTNF-α agent given: etanercept group A(12 patients), infliximab group B(10 patients), and both group C [not at the same time] (3 patients). The patientsreceived their treatment for 6 months consecutively. Patients were selectedas candidate for anti-TNF-α therapy according to the first update of theASAS consensus statement for the use of anti-tumor necrosis factor (TNF).Readings from the Bath AS indices (function, disease activity, metrology &radiology) in addition to Health Assessment Questionnaire forSpondyloarthropathies HAQ-S, ACR 20 response criteria for tender andswollen joint count and Laboratory variables for inflammation (CRP) wererecorded before starting the treatment and after six months. Our results showed a significant positive correlation between thevalidated composite measure ASAS response criteria (pain, patient globalassessment, function and inflammation), BASMI, BASDAI, HAQ-S and antiTNF-α therapy. Function and morning stiffness (inflammation) wereimproved greatly in younger age group patients after receiving the treatment(P= 0.006, P=0.016 respectively). Also a significant positive correlation wasfound between CRP titer and anti TNF-α treatment. While disease durationand specific anti TNF-α agent given to the patient did not show anysignificant correlation regarding their function (P= 0.83, P= 0.48respectively) nor their morning stiffness (P= 0.89, P= 0.93 respectively). TNF-α blocking therapy has a significant impact on AS patientsregardless their disease duration with no superiority of specific anti TNF-αagent than the other (according to the two agents used in our study). Younger age group patients showed improvement in their function,inflammation and mobility than older ones after receiving the treatment.