Introduction: Regarding the functioning of the endocrine system, and especially in the thyroid of patients with thalassemia, multiple studies in different parts of the world have reported conflicting results. The aim of this study was to assess the levels of thyroid hormones and TSH in beta-thalassemic patients in the city of Ahwaz. Methods: In this matched case-control study, 105 patients in the case group and 105 subjects as controls were randomly selected from clients referred to the Abuzar hospital in 2015-2016. Serum levels of T3, T4, and TSH hormones were measured using ELISA. Data was processed with the SPSS15 software and tested by using independent t-tests and logistic regression. Results: The study results showed that the serum level of T3 hormone did not significantly differ between the two groups (p> 0.05). Whereas the serum level of T4 was lower in the case group, compared to the controls, which was statistically significant (p