A fraction of patients with rectal cancer can achieve clinical complete response following longcourse chemoradiotherapy (CRT), and there is accumulating clinical evidence that these patients can be managed non-surgically with acceptable oncological outcome. Consequently, strategies for increasing the proportion of complete responders are actively being explored. Some, although limited, experience with high-dose radiotherapy indicates that there might exist a dose-response relationship for local tumour control after radiotherapy alone. Thus, tumour dose escalation could be indicated for selected patients, particularly in cases with small tumours and limited local disease. This report discusses several radiotherapy techniques for tumour boosting, focusing on technical challenges and clinical experiences with each technique. Specifically, external beam radiotherapy, brachytherapy and contact X-ray treatment for dose escalation are considered. Ultimately, no technique provides definitive advantage over others, and the choice in clinical practice will have to depend on the patient population treated as well as the technical capabilities of the treating department.