Progress has been made in the delivery of brachytherapy, from low-dose rate (LDR) to high-dose rate (HDR) treatments, allowing for dose optimisation, conformal treatments, improved radiation protection, and improved accuracy and efficiency. Image-guided brachytherapy, incorporating spatial and temporal changes, is now possible with advanced imaging and treatment technology. This report reviews the evidence for the benefits of image-guided brachytherapy using magnetic resonance imaging (MRI), mainly for cervix and prostate cancer, but also possibilities for other tumour sites. It also emphasises the need for a dedicated MRI unit for brachytherapy.