Background: Biological inflammatory status in cancer patients is evaluated with various parameters. Limited studies have been conducted on this issue in children. Objectives: This study was done to evaluate the importance of the biological inflammatory status, including systemic inflammatory response index (SIRI), systemic immune-inflammation (SII) index, and hemoglobin-albumin-lymphocytes-platelets (HALP) score in children with cancer. Methods: Demographic characteristics, complete blood count, and biochemical analysis of the patients on admission were recorded retrospectively. Since not meeting the necessary assumptions, the Mann-Whitney U test was used for the comparison of the two groups, and the Kruskal-Wallis test was used for the comparison of more than two groups Results: The SIRI of the patients was statistically higher than the control group (P < 0.0001). Considering lymphoma, central nervous system tumors, and solid tumors, there was a statistical difference between the groups in SII index and SIRI (P values: .0245, and .0060, respectively). Regarding inflammatory biomarkers, according to the extent of cancer (localized or advanced disease), it was found that SIRI was higher in patients with advanced disease (P=0.0175). The patients who died had a statistically higher HALP score (P=0.0472). Conclusions: The inflammatory biomarkers can be used in childhood cancers to determine the extent of the disease and predict outcomes. However, in larger patient series, ideal values should be achieved by analyzing the receiver operating characteristic curves and the area under the curve.