The deleterious effects of cardiac iron load on the ventricular repolarization were demonstrated in beta-thalassemia major (β-TM), but little is known about the P wave measurements, an independent risk factor for development of atrial fibrillation (AF). We aimed to examine relationship between P-wave parameters and iron loading using cardiac T2* Magnetic Resonance Imaging (MRI) in asymptomatic β-TM patients. The study involved 22 β-TM patients and 22 age- and gender-matched healthy controls. Although P-wave parameters were within normal limits, P max, P min, and Pi were significantly prolonged in the β-TM group compared to the healthy controls (p=0.005, p=0.01, and p=0.03, respectively). Pd was found similar between groups (p=0.46). The prevalence of partial IAB was increased in patients with β-TM (p=0.001) and complete IAB was detected only in one patient. P-wave parameters of patients with cardiac T2*<20 msec and T2*>=20 msec were comparable in patients with β-TM. There was no correlation between P-wave parameters and cardiac T2*MRI values. The present study demonstrated that P-wave measurements were slightly affected in β-TM patients with preserved LV functions and this influence was not related with cardiac T2*MRI values. We concluded that the effect of β-TM on the AF development is still controversial.