Acute leukemia is the most common malignancy found in children. A Complete Blood Count (CBC) examination can calculate the lymphocyte-to-leukocyte ratio, neutrophil-to-leukocyte ratio, and neutrophil-to-lymphocyte ratio to monitor the progress of Acute Lymphoblastic Leukemia (ALL). C-reactive protein is a marker of inflammation and can determine disease progression during treatment. The study's analytical design was observational, with a cross-sectional design conducted at the laboratory of the Clinical Pathology Faculty of Medicine, University of Udayana, and Ngoerah Hospital from March to August 2020. The study included 48 subjects, divided into three phases: induction, consolidation, and maintenance, in ALL patients. Specimen collection was collected in 2 tubes. Kolmogorov-Smirnov statistical analysis was used to assess normality, and homogeneity was evaluated with Levene’s test. The difference test was performed using the Kruskal-Wallis test. This study aimed to determine the relationship between parameters was performed with Spearman correlation. This study showed a strong correlation between hemoglobin levels and neutrophil/lymphocyte ratio (r= 0.358, p=0.015), hemoglobin and lymphocyte/leukocyte ratio (r= -0.287, p=0.048), hemoglobin and CRP (r= -0.493, p=0.000). Significant correlation between reticulocyte percentage and neutrophil/lymphocyte ratio (r= 0.505, p=0.000), neutrophil/lymphocyte ratio and CRP (r= -0.870, p=0.000), neutrophil/leukocyte ratio and lymphocyte/leukocyte ratio (r= 0.960, p=0.000). Significant correlations have been found between hemoglobin levels and the neutrophil/lymphocyte ratio (NLR), which is a measure of the lymphocyte/leukocyte ratio (LLeu-ratio), along with CRP. This relationship has been connected to inflammation in ALL patients following chemotherapy. CBC is an easy-to-use test to determine whether inflammation is present in ALL patients following chemotherapy.