Background: Beta thalassemia is one of the most common hereditary chronic hematological disorders in our country. Leptin is considered a physiological link between nutritional status and reproductive maturation and function. Objective: We conducted this study to evaluate serum leptin in pediatric beta thalassemia patients who are transfusion dependent. Patients and Methods: We selected 32 cases of pediatric patients of beta thalassemia above age of eight years and had delayed growth, and we excluded all individuals suffering from any other problem affecting growth and development. Our patients were being followed up at hematologic outpatient clinics in Zagazig University Hospital and Mansoura Insurance Hospital, in the period from December, 2018 to June, 2020. We compared them by 28 healthy controlled individuals sharing the same age and sex who attended outpatient general clinics. Results: Coincidence of participants at age and sex but there was significant decrease in height, weight and BMI of cases than control group. Serum leptin was significantly lower in cases of beta thalassemia than control group (P<0.001). ROC curve was used for detection the validity and cutoff point of serum leptin in differentiating cases. Area under the ROC curve (0.987) was excellent. Conclusion: Decreased serum leptin in patients of thalassemia. Cutoff point (982.5) was the best value to detect validity of serum leptin to differentiate cases, with sensitivity of 96.9%, specificity of 89.3%, accuracy of 93.3%, positive predictive value of 91.2% and negative predictive value of 96.2%.