Background. Some calculated total blood count readings are investigated as additional readings to help with evaluation of CAD patients clinical management and prognosis. Aim. We aimed to investigate the association between readings such as NLR, MLR, PLR, NMR, LMR, MHR, SII, SIRI and the severity of CAD in patients with SAP. Methods. This retrospective pilot study included 166 patients. All these patients underwent CA or CCTA, or both, to assess severity of CAD. Patients were divided into three ways: 1) according to presence (n=146) or absence (n=20) of CAD; 2) according to Gensini score; 3) according to the CAD-RADS score. Results. Patients with CAD had lower LMR, higher NLR, SIRI, MLR and SII compared to patients without CAD (p<0.001 and p=0.018, respectively for SII). According to the CAD severity by Gensini score, the NLR, MLR, SII and SIRI values increases and LMR decreases gradually with severity of CAD (p<0.001). It was found moderate correlation between SII (r=0.511, p<0.001), NLR (r=0.567, p<0.001) and SIRI (r=0.474, p<0.001) and severity of CAD according to Gensini score. MLR and LMR low correlated with severity of CAD according to Gensini score (r=0.356, p<0.001; r=-0.355, p<0.001, respectively). The CAD-RADS score weakly correlated with NLR and MHR (r=0.365, p<0.001; r=0.346, p<0.001, respectively), and moderately with LMR, MLR and SIRI (r=-0.454, p<0.001; r=0.455, p<0.001; r=0.522, p<0.001, respectively). Conclusions. NLR, LMR and SIRI appear to be potential predictors of chronic inflammation, and SIRI is the best predictor of the degree of atherosclerosis of all the other assessed blood parameters. Keywords: Total blood count readings, systemic immune-inflammation index, coronary artery disease, atherosclerosis, SIRI.