PURPOSE: Acute rhinosinusitis (ARS) is a common pediatric disorder. When complications occur, it can lead to various morbidities. Therefore, easily accessible and inexpensive markers are needed to predict the development of complications, treatment, and clinical course of acute rhinosinusitis. We aimed to investigate the predictive ability of the various inflammatory markers in pediatric complicated ARS patients. METHODS: The data of 79 pediatric patients with complicated ARS and 116 pediatric patients with uncomplicated ARS were analyzed retrospectively. The complete blood count and C-reactive protein (CRP) test results at the time of diagnosis were recorded. Also, a receiver operating characteristic (ROC) analysis was performed. RESULTS: The complicated ARS group consisted of 65 (82.3%) patients with preseptal cellulitis, 4 (5.1%) with orbital cellulitis, 5 (6.3%) with subperiosteal abscess, and 5 (6.3%) with orbital abscess complications. At the time of initial diagnosis, there was a significant difference in WBC, NLR, CRP, %LUC, SII and SIRI values between complicated ARS and uncomplicated ARS patient groups (p <
0.05). In terms of predictive power, the area under the curve (AUC) was 0.805 (95% confidence interval (CI) 0.74-0.87, p <
0.001) for CRP, 0.62 (95% confidence interval (CI) 0.54-0.7, p = 0.004) for systemic immune-inflammatory index (SII) and 0.67 (95% confidence interval (CI) 0.6-0.75, p <
0.001) for systemic inflammatory response index (SIRI). CONCLUSION: In conclusion, our study shows that inflammatory markers can be helpful in the evaluation of pediatric rhinosinusitis patients. CRP, SII and SIRI were adequate markers of inflammation to predict the development of complications in patients with pediatric rhinosinusitis.