Background. Iron deposition in the body can damage the endocrine glands of patients with β-thalassaemia major (β-TM). Leptin plays a key role in the regulation of appetite, body fat mass, and endocrine function. Objectives. This study aimed to evaluate the relationship between serum leptin and growth and pubertal development in patients with β-TM, as well as whether serum leptin can predict growth retardation and delayed puberty in these patients. Methods. Fifty β-TM patients (aged 8-20 years) and 75 age-matched healthy controls were recruited. Anthropometric data and sexual maturity ratings were assessed. Serum leptin was measured by ELISA. Results. Serum leptin levels were significantly lower in patients with β-TM than in healthy individuals (P < 0.001). Leptin levels were also significantly reduced in female patients with short stature (P < 0.002) and in patients who displayed delayed puberty (P = 0.032) compared to those with normal stature who had reached puberty. The sensitivity of leptin for predicting short stature and delayed puberty among patients was 84.6% and 92.3%, respectively. Conclusion. Low serum leptin is sensitive to predict short stature and significant in β-TM females only. This link could thus be used as a guide for further therapeutic or hormonal modulation.