Abstract : Determining the frequency of hypogonadism in thalassemia major patients and clarifying factors affecting it can be helpful in reducing related complications and improving the prognosis. The objective of the present study was to establish the frequency of hypogonadism in thalassemia major patients of Hazrat-e Rasool Akram Hospital during 2013-2017. A descriptive and analytic cross-sectional observation was carried out for this study and 285 thalassemia major patients were selected via convenience sampling. The frequency of hypogonadism among samples was assessed and the relationship between hypogonadism and different factors was analyzed. One hundred forty-six patients (51/2%) had hypogonadism. A statistically significant relationship was found between tallness and hypogonadism; taller patients suffered from hypogonadism more than shorter ones (P=0.025); but weight, Initial serum ferritin level, LH, FSH, testosterone, splenectomy and the type of Injectable product had no significant relationship with of hypogonadism occurrence in the studied patients (P > 0.05). Based on the results, it is inferred that hypogonadism can be found in half of thalassemia major patients and therefore proper measures must be taken in order to decrease its prevalence