PURPOSE: To describe the development of a proctitis-specific quality-of-life module to supplement the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30). METHODS AND MATERIALS: The module was developed according to EORTC guidelines, which consisted of an extensive literature review to identify previously described issues and interviews conducted with seven health professionals and 10 patients to rationalize the item list for construction into a provisional module. The module developed was then pretested with 28 patients and five health professionals. RESULTS: The final module contains 21-items that are suitable to obtain information about the patients' quality of life after high-dose pelvic irradiation. The questionnaire has now been translated into four languages and commenced field testing in late 2007. CONCLUSIONS: The EORTC QLQ-C30, supplemented by EORTC QLQ-PRT21, will enable health professionals to more accurately monitor the side effects that patients experience after pelvic irradiation.