Background: Thalassemia is the most prevalent single gene defect in human beings worldwide. Repeated blood transfusions along with chelation therapy are mainstay of treatment in thalassemia patients. However, these recurrent blood transfusions along with inadequate chelation therapy results in iron overload. The study aimed to investigate the serum ferritin level in children with blood transfusion in thalassemia major patients and to know their correlation with age and growth. Materials and methods: A cross-sectional analytical study was conducted including 79 children of thalassemia major in the age group of 5-12 years who were on regular blood transfusion and oral iron chelators from thalassemia unit of Chittagong Medical College Hospital. Serum ferritin was tested and their correlation with age and growth was assessed. Chi square was done to determine the correlation. Results: The age of the patients ranged from 5 to 12 years and 45(56.9%) were males. The mean age at diagnosis of thalassemia was 10.7±4.2 months and mean number of transfusion was 90±29 and ranged between 40-140 transfusions. All of the children were on oral iron chelation therapy and the average age of initiation chelation therapy was 5.7±1.1 years. 64(81%) children had growth retardation. Mean serum ferritin level was 3740.7±2185.8 ng/ml and only 3.8% of the patients had serum ferritin level <1000 ng/ml. Conclusions: This study concludes that serum ferritin is raised and positively correlated with age and growth in thalassemia major patients. So routine evaluation of serum ferritin tests may be advocated for thalassemic patients. Chatt Maa Shi Hosp Med Coll J; Vol.23 (2); July 2024; Page 34-38