-Hypothyroidism the most common thyroid dysfunction appears in thalassemia. The current study aimed to estimate thyroid function through detecting the presence of anti-thyroid peroxidase, anti-Thyroglobulin, T3, T4 and TSH.Material and Subject: Cross sectional study carried out on 100 patients with thalassemia major (52 male and 48 female) with average age (13.9 ± 10.0) years. Tests of thyroid function (TSH, T4, and T3) were estimate via using an automated quantitative COBAS e411. While,

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... yroglobulin and Anti-Thyroid peroxidase were estimated by using ELISA technique. Results: Euthyroid was enrolled in 67 (67%) of 100 patients who suffer from thalassemia major. While, 31 (31%) have subclinical of hypothyroidism and only 2 patients (2%) patients were overt hypothyroidism. Among these 100 patients, Anti-thyroid peroxidase was detected in 26 patients (26%) and anti-thyroglobulin test was positive in 18 patients (18%). Conclusion: Thyroid dysfunction is frequent in thalassemia patients. The main thyroid dysfunction hypothyroidism and autoimmune disease also frequents in thalassemia patients.