Background: After colorectal surgery, patients often experience impaired functional outcome. Faecal incontinence grading systems and self-assessment questionnaires are frequently used to assess these complaints. The available faecal incontinence grading systems have been validated, but have a limited focus, while more comprehensive questionnaires, which have been developed, have not been validated. Aims: To investigate the reliability and validity of a newly developed, colorectal functional outcome (COREFO) questionnaire and of Dutch translations of the Hallböök questionnaire and an adapted version of the Vaizey questionnaire. Patient/methods: Two hundred fifty-seven patients with and without impaired functional outcome after (colorectal) surgery received a booklet containing the three questionnaires in random order by mail. One hundred seventy-nine (70%) completed them, and 160 patients (90%) completed a retest within, on average, 18 days. Results/findings: Reliability and validity were adequate for the COREFO and Hallböök questionnaire, with slight differences in the psychometric analyses in favour of the COREFO questionnaire. Significantly more patients found the COREFO questionnaire to reflect their problems best. The reliability of the Vaizey questionnaire was not sufficient. Interpretation/conclusions: The newly developed COREFO ques tionnaire and the previously unvalidated Hallböök questionnaire are both suitable instruments to evaluate functional outcome after colorectal surgery. The psychometric analyses showed a slight difference in favour of the COREFO questionnaire and significantly more patients preferred the COREFO questionnaire to the other questionnaires. Therefore, we prefer to use the COREFO questionnaire in future research.