Pulmonary arterial hypertension (PAH) is a progressive disease with high morbidity and mortality rates. Research has shown that PAH has a prevalence rate of 10-79% in thalassemia major patients. This cross-sectional study was carried out in 2014 to determine the prevalence and risk factors of PAH in all thalassemia major patients of over 18 years of age in Ilam, Iran. A cardiologist measured systolic pulmonary artery pressure (SPAP) by using Doppler echocardiography. SPAP of higher than 25 mm Hg was defined as PAH criterion. The obtained data was analyzed using SPSS, version 17. Of the 36 studied patients, 17 (47.2%) were male and 19 (52.8%) were female. The mean age of the patients was 26.0±5.6 years. The prevalence of PAH in the thalassemia major patients was estimated to be 47.2% and the mean SPAP was determined to be 26.2±14.6 mm Hg. Among the examined PAH risk factors, only the history of pulmonary disease (0.02) and transfusion (0.03) was found to be significant.