Purpose Chronic rhinosinusitis with nasal polyps can be classified as eosinophilic or neutrophilic based on the major inflammatory cell type in the tissue. There is a need for predictive parameters to enable rhinologists to identify the type of nasal polyp in a patient without surgery. The aim of the present study was to test the predictive value of the markers of inflammation to estimate eosinophilic nasal polyps. Methods The study analyzed 299 patients who underwent sinus surgery for nasal polyps from 2012 to 2019. Patients were divided into two groups according to pathology results (eosinophilic polyps = group 1, neutrophilic polyps = group 2). The values of preoperative complete blood count, systemic immune inflammation index, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio were compared. Results In our series, results of ROC analyses for both mean eosinophil count and systemic immune inflammation index were statistically significant. For the eosinophil count (AUC = 0.681,p < 0.001) and systemic immune inflammation index (AUC = 0.621,p = 0.001). Patients with an eosinophil cut-off value of 0.25 cells x 10(9)/L had ORs of 49.27 (95% CI 11.68-207.81) and sensitivity: 0.69, specificity: 0.64. Patients with a systemic immune inflammation index cut-off value of 332.39 had ORs of 1.003 (95% CI 1.002-1.004) and sensitivity: 0.84, specificity: 0.39. Conclusion The systemic immune inflammation index and absolute blood eosinophil count could be used to predict nasal polyp subtypes before surgery. We believe that systemic immune inflammation index should also be studied to estimate postoperative recurrence.