The international standard regimen of radiotherapy for women with early breast cancer following mastectomy or local tumour excision involves the delivery of daily doses (fractions) of 2.0 Gy to a total dose of 50 Gy. Recent randomised clinical trials suggest that there is most unlikely to be any disadvantages in terms of local tumour control or late adverse effects, and obvious advantages in terms of convenience, for schedules treating to a lower total dose using a smaller number of larger fractions. Fifteen or 16 fractions of 2.67 Gy are being adopted in some countries, and future research will test the limits of this approach, termed accelerated hypofractionation.