Systemic Lupus Erythematosus (SLE) is a chronic autoimun inflammation disease. Ferritin is an acute protein phase that increased in inflammatory process and autoimmune disorder. To investigate the correlation of serum ferritin levels and disease activity of systemic lupus erythematosus based on SLEDAI score. The study design was an analytic observational cross sectional design in 30 pediatric patients who have been diagnosed with systemic lupus erythematosus (SLE) in outpatient and inpatient allergy and immunology units at Haji Adam Malik Hospital from January-July 2022. Their disease activity was calculated by using the SLEDAI score and their serum ferritin levels were measured. The correlation of serum ferritin level and disease activity was analyzed by using spearman correllation with CI 95%, p<0.001. A total of 30 chidren were included in this study. The sample There were girl more than boy 4:1. The average age was 14,77 years old. The mean serum ferritin level was 2308,7 mcg/L and SLEDAI score was 14,73. Based on the study, we conclude that there was positive correlation between ferritin serum and disease activity of systemic lupus erythematosus in children, with significant correlation (p< 0,001) and r value = 0,815 that show us there was strength correlation between serum feritin levels and SLEDAI scores. There was significant correlation of serum ferritin level with disease activity of systemic lupus erithematosus in children.