While there is now Level I data with longâterm followâup supporting the routine use of hypofractionated (HF) wholeâbreast radiation therapy (WBRT) after breastâconserving surgery, its adoption has been slow and variable. This article will review the literature supporting the efficacy and safety of hypofractionated radiation for breast cancer, discuss the radiobiological rationale specific to breast tumors, and make an argument for justifying the routine adoption of shorter, HFâWBRT courses when delivering breast radiation. Data using HF with regional nodal irradiation and in the postâmastectomy setting will also be reviewed. The aim is to provide an inâdepth understanding of the use of hypofractionated radiation therapy for breast cancer, its applicability, and topics warranting future research.