Objective: Septic arthritis is a surgical emergency that can result in significant morbidity if not treated promptly and appropriately. With appropriate surgical and antibiotic therapy, inflammatory markers are expected to rapidly normalize in the patients with septic arthritis. Lack of or slow normalization may signify treatment failure. Our aim was to investigate if high neutrophillymphocyte and platelet-lymphocyte values can be used to predict sustained elevation of CRP levels. Method: Fifty-seven pediatric patients operated in our clinic with the diagnosis of septis athritis between 2003 and 2016 were included in the study. Neutrophil, lymphocyte and platelet counts as well as CRP and ESR values at presentation, 1 and 2 weeks were scanned Neutrophil-lymphocyte and platelet-lymphocyte values were calculated. Results: Average age of the patients were 7 years (1 month-16 years). Of the 57 patients 41 were male (71.9%) and 16 were female (28.1%). The knee joint was the affected in 38 (66.7%) and hip joint in 19 cases (33.3%). Left and right sides were affected in 29 (50.9%), and in 28 cases (49.1%), respectively. At presentation average (range) neutrophil (9.5 106/L; 1.1-34.9 106/L), platelet (425.7 109/L; 31-830 109/L) and lymphocyte (3.1 106/L:0.1-9.8 106/L) counts were calculated as indicated. Average CRP value at 14 days was 38 (3-164) mg/dL. ROC curve analysis showed that a threshold level of neutrophil-lymphocyte ratio of >4,3 at presentation is 71% sensitive and 70%spesific for prediction of CRP levels of >20 mg/L at 2 weeks. Conclusion: A threshold of neutrophil-lymphocyte ratio of >4.3 at presentation is fairly sensitive and specific for prediction of CRP levels above >20 mg/L at 2 weeks. Possibility of slow normalization and even persistence of higher levels of CRP, in this patient group should be kept in mind.