The aim of this project was to develop and evaluate a decision‐making guide for patients with colorectal cancer contemplating adjuvant therapy. Initially, a focus group was held, and then a draft booklet was developed, which was reviewed by patients and professionals. A subsequent revised booklet and a questionnaire were mailed to 24 patients and 32 professionals for evaluation. Further changes resulted in the final 100‐page decision‐making guide, which had a Flesch‐Kincaid reading level of 8.0 and DISCERN rating 5. Seventeen patients (71%) and 22 professionals (69%) completed the questionnaire. All patients agreed/strongly agreed the guide was ‘informative’ and ‘written in a way you like’ and 94% considered it ‘helpful for making decisions’. Professionals found it ‘informative’ (95%), ‘written in a pleasing style’ (95%), ‘easy to understand’ (91%) and felt it would ‘help patients make decisions’ (76%), ‘be appropriate to give to patients’ (91%) and would ‘improve patient knowledge and preparedness’ (100%). Further work aims to assess the impact of the guide upon patient outcomes.