Radiotherapy Planning is the new title in the Oxford Specialist Handbooks in Oncology series. It provides a comprehensive guide to modern radiotherapy practice, firmly based on unchanging principles. The author discusses advanced radiotherapy techniques as well as simpler field-based arrangements, so that this handbook can be used globally for clinical practice, including countries with limited resources. The site-specific chapters are structured in two parts. Firstly, current treatment approaches are discussed, with particular attention to the relevant underlying principles to ensure it remains appropriate and useful despite changes in other cancer treatments. The second part of each chapter discusses the most important clinical trials which have informed the current approaches to treatment at the time of publication. In addition, there is a section on imaging features of different tumours, which is useful for clinicians to choose appropriate images for target volume delineation. This handbook will give an accessible introduction to new trainees in the specialty, and it will continue to encourage in all clinical oncologists logical thinking, the ability to ask challenging questions, appropriate analysis of outcomes, and delivery of treatment assessed according to its clinical benefit to patients and its academic rigour.