Background: The albumin to fibrinogen ratio (AFR) and C-reactive protein to albumin ratio (CAR) have emerged as useful biomarkers of systemic inflammation. The aim here was to investigate the relation between AFR/CAR and ASDAS-ESR Score in ankylosing spondylitis (AS). Methods: This case control study included 30 patients with AS and 30 healthy controls. We calculated CAR and AFR in each group and comparison between both groups was done. The correlations between AFR, CAR and the disease activity were analyzed. Receiver operation characteristic (ROC) curves of albumin/fibrinogen ratio and CRP / albumin ratio were performed to set the best cutoff value for detecting disease activity of AS. Results: The AFR was significantly lower in AS in AS patients than those in the control group while CAR was significantly higher in AS patients than those in the control group. ROC curve of CRP/albumin ratio to detect disease activity in AS patients showed AUC 0.71. So, CRP/albumin ratio was a fair parameter to discriminate disease activity among AS patients. ROC curve of albumin/fibrinogen ratio to detect disease activity in AS patients showed AUC 0.85. So, albumin/fibrinogen ratio was a good parameter to discriminate disease activity among AS patients. Conclusion: AFR and CAR are two novel inflammatory markers for monitoring disease activity in AS patients. AFR and CAR are parameters that can be assessed quite simply, rapidly and inexpensively. CAR was a fair parameter while AFR was a good parameter to discriminate disease activity among AS patients.