Abstract : One of the most common and safe techniques applied in many surgeries is spinal anesthesia. However, it may create some complications like nausea and vomiting. Postoperative nausea and vomiting (PONV) is known as a prevalent complication after anesthesia and surgery. Many studies have introduced Inflammation as a significant factor in the occurrence of PONV. Neutrophil-to-lymphocyte ratio (NLR) is a prognostic biomarker taken from peripheral blood, to check the inflammation in various diseases. This study was conducted with the aim of examining the role of spinal anesthesia in creating inflammation and the incidence of PONV. This study was conducted on 80 patients to identify the relationship between NLR values and PONV prevalence. The values of Neutrophil, Lymphocyte, and NLR, obtained from Four blood sampling, were compared together and also to the blood samples of Non-PONV patients. The prevalence of PONV was 33.75%. The average of systolic blood pressure (P=0.25), diastolic blood pressure (P=0.69), and heart rate (P=0.73) did not show significant differences between the two groups, but the oxygen saturation level (P=0.02) was significantly lower in the group with PONV. In this group, from the second sample onwards, the number of Lymphocytes was significantly lower (P<0.001), and the number of Neutrophils (P=0.01) and the NLR (P<0.001) were significantly higher. Considerable changes in Neutrophils, Lymphocytes, and NLR values in patients with nausea and vomiting after spinal anesthesia are significantly associated with antiemetic usage and better post-treatment.