Background: The current gold standard for adjuvant radiotherapy for breast cancer in nowadays is hypofractionated radiotherapy. Objectives: Here, we discuss early, late, and cosmetic results  of 1 week adjuvant breast radiotherapy and to find the predicted indicators for toxicity . Patients and methods: The study included 63 breast cancer patients. Invasive breast cancer patients who undergone mastectomy or breast conserving surgery (pT1-3, pN0-1, M0), were eligible if they were at least 18 years old. Patients got 26 Gy/5F/1-week. Individuals who underwent breast conservation and are younger than 50 years old may employ a sequential boost (dosage of 5.2 Gy/ 1 fraction). After radiation, physician-rated early and late toxicity as well as the cosmetic result were prospectively evaluated. Results: 63 patient assessed early after 6 weeks from end of radiotherapy for acute skin toxicity with grade 2 was 27 % with univariate  analysis show no significant association between occurrence of acute toxicity and different factors and after median follow up 25 months , the late toxicity assessment show that moderate & marked radiotherapy related fibrosis represent 6.3%, Telangiectasia(3.2%) and hyperpigmentation(6.3%) with univariate  analysis show no significant association between occurrence of late toxicity and different factors. The rate of fair or poor cosmesis was 12.7%, univariate analysis of cosmetic outcome revealed only significant association between cosmosis and chemotherapy . Conclusion: The findings support the viability and safety of 26 Gy in five fractions radiotherapy over 1 week in adjuvant setting in  early breast cancer.