Current treatment for high-grade non-muscle invasive bladder cancer utilizes bacillus Calmette-Guerin (BCG) installations into the bladder. Although effective, BCG toxicities often cause delay or instillation interruptions and this can consequently reduce the treatment efficacy. The importance of a patient questionnaire for identifying symptoms following BCG intravesical therapy, minimizing toxicities and improvements in patient compliance are recognized. However, as yet, a standard questionnaire is not available. The European Association Urology Nurses guidelines have suggested a survey; however, its terminology is potentially too complex to be used by the patients. A project with 3 phases was developed in order to identify the most user-friendly survey to be used in this population group. Phase 1: Identification and assessment of existing BCG side effects questionnaires. Phase 2: Adaptation and assessment of a BCG side-effect questionnaire. Phase 3:Testing of the adapted questionnaire. Following the review in phase 1, four questionnaires' were found and assessed using appraisal and text readability tools. Appraisal showed that the four surveys used difficult language for patients to use independently.Based on patient feedback, a BCG side-effect questionnaire was adapted to be more patient-friendly and appraised using the same tools from phase 1. The adapted questionnaire proved to be beneficial for both patients and health professionals. First, it was more easily understood by patients. Second, it enabled staff to better identify patients at risk, monitor treatment consequences and implement supportive measures. Despite the adaptations, however, patients continued to find the terminology used ambiguous.