Radiation therapy is an integral part of management in breast carcinoma treatment. Standard curative schedules of radiotherapy to the breast deliver 25 fractions of 2.0 Gy per day over 5–6 weeks. Considerable recent literature suggests that hypo-fractionation may be advisory in breast cancer. The use of fewer fractions of more than 2 Gy per day (hypo-fractionation) is based on data suggesting that breast carcinoma is more sensitive to fraction size than squamous carcinomas and therefore could have similar fractionation sensitivity to the dose-limiting healthy tissues, including skin, subcutaneous tissues, muscle and ribs. In this article, a review of published studies and currently ongoing trials, which may provide evidence for the use of hypo-fractionated radiotherapy in breast cancer patients, is presented. Also, for all these different hypo-fractionation regimens found in literature, biologically effective dose (BED) values are calculated and compared. Data from studies and randomised trials seem to support the concept that modest hypo-fractionation can be used to treat the whole breast after breast-conserving surgery with similar rates of local control and radiation morbidity as seen with conventional fractionation.