This study aimed to determine the difference CRP values before and after eradication therapy of Helicobacter pylori gastritis in children. A quasi-experimental study with a separate sample pretest-posttest design was carried out by collecting medical records of children aged 2-18 years diagnosed with H. pylori gastritis from October-December 2020. Data on serum CRP levels before and after H. pylori gastritis eradication therapy were collected from patient medical records. Comparison between groups of H. Pylori gastritis before and after eradication therapy was performed using T-dependent/Wilcoxon test. Test the normality using the Saphiro-Wilk test. There were 37 data that met the inclusion and exclusion criteria. The CRP value in children with H. pylori infection (+) before eradication therapy was 19.31 mg/dL (10.05-128). After giving eradication therapy, the value of CRP decreased to 11.2 mg/dL (6.8-30.4). Using the Wilcoxon test showed that there was a significant difference in CRP values between before and after eradication therapy (p < 0.001). There was a significant difference in CRP values between before and after H. pylori eradication therapy in children.