Thalassemia major patients receive regular blood transfusions every 2-5 weeks, to maintain pretransfusion hemoglobin levels above 9-10.5 g/dl. In patients with thalassemia major, continuous blood transfusion can cause iron overload by increased serum ferritin levels. Accumulated iron is toxic to many tissues causing dysfunction and failure of major organs, including the heart, kidneys, liver and endocrine glands (pituitary, thyroid, parathyroid, and pancreas). This study aims to determine the relationship between ferritin levels with creatinine, SGOT and SGPT in patients with thalassemia major. This research is observational with data collection using a cross-sectional method. The study population was 65 medical records of thalassemia major patients at Hermina Jatinegara Hospital, Indonesia, in 2019. The analytical method used is the Kruskal Wallis test and the Spearman correlation test. The results obtained were that the average levels of ferritin, creatinine, AST and ALT were 2952.23 ng/mL, 0.52 mg/dL, 32.37 /L and 32.33/L. The results of the Kruskal-Wallis test showed that the levels of ferritin and creatinine had a significant difference based on age (p 0.041 and p 0.049). The Spearman correlation test results showed a positive correlation between serum ferritin and SGPT (p 0.02) with a coefficient correlation of 0.289. There is no correlation between serum ferritin, SGOT and Creatinine (p 0.17 & p 0.73). Based on these results, serum ferritin levels have a weak correlation with SGPT levels and do not correlate with other parameters.