To asses cardiac toxicity post radiotherapy in left cancer breast patients with different fractionations. This is a prospective randomized study conducted at Kasr El-Ainy Center of Clinical Oncology and Nuclear Medicine [NEMROCK] . Cardiological assessment using RTOG toxicity criteria was done for left sided breast cancer patients after at least five years of conformal radiation therapy. There were two arms of radiation, conventional [50Gy/25sttt/5 Ws] and hypofractionation [42.5 Gy 716 fractions /3 1/5 weeks] . Thirty patients were included in each arm. After a median follow up of 62 months [range 60 to 72] , cardiac dysfunction developed more in the conventional arm but was insignificant [P value =0.36] . Grade I and II toxicity was 83.3 vs 70% and grade III was 3.3% in the hypofractionated arm only. The rate of local-regional tumor relapse at 5 years was similar [3.3%] . Hypofractionated radiotherapy decreased cardiac toxicity though not statistically significant, however it is more cost effective and time consuming