The authors investigated the prevalence of low bone mass in patients from Tehran, Iran, with β-thalassemia major (n = 203), aged 10–20 years, and the potential risk factors for osteoporosis in this patient population. Prevalence of osteoporosis was 50.7% in lumbar spine, 10.8% in femur, and 7.9% in both regions with no significant difference between the two genders. The following factors were associated with low BMD: height for age and weight for age below 3rd percentile, delayed puberty or hypogonadism, age when Desferal (for iron chelation) was started, duration of Desferal therapy, and serum zinc. Low serum copper and 25(OH)D were not associated with low BMD.