Background: Aortic valve stenosis (AVS) is the most common cause of left ventricular outflow obstruction, and its prevalence among elderly patients causes a major public health burden. Recently, platelet-to-lymphocyte ratio (PLR) has been recognized as a novel prognostic biomarker that offers information about both aggregation and inflammation pathways. Since PLR indicates inflammation, we hypothesized that PLR may be associated with the severity of AVS due to chronic inflammation pathways that cause stiffness and calcification of the aortic valve. Materials and Methods: We retrospectively enrolled 117 patients with severe degenerative AVS, who underwent aortic valve replacement and 117 control patients in our clinic. PLR was defined as the absolute platelet count divided by the absolute lymphocyte count. Severe AVS was defined as calcification and sclerosis of the valve with a mean pressure gradient of > 40 mmHg. Results: PLR was 197.03 +/- 49.61 in the AVS group and 144.9 +/- 40.35 in the control group, which indicated a statistically significant difference (P < 0.001). A receiver operating characteristic (ROC) curve analysis demonstrated that PLR values over 188 predicted the severity of aortic stenosis with a sensitivity of 87% and a specificity of 70% (95% confidence interval = 0.734- 0.882; P < 0.001; area under ROC curve: 0.808). Conclusion: We suggest that the level of PLR elevation is related to the severity of degenerative AVS, and PLR should be used to monitor patients' inflammatory responses and the efficacy of treatment, which will lead us to more closely monitor this high-risk population to detect severe degenerative AVS at an early stage.