Measurement of health-related quality of life (HRQL) is becoming more important in studies of patients with inflammatory bowel disease. The McMaster IBDQ is the most widely used HRQL instrument for these patients. However, its use with patients in the United Kingdom has not been validated. This study develops and validates a UK version of the McMaster IBDQ (UK IBDQ). The UK IBDQ was tested with two samples of patients for its reliability, validity, reproducibility, and responsiveness. The first sample consisted of 180 patients participating in a randomized clinical trial. The second was recruited from members of the National Association for Colitis and Crohns Disease. Reliability of the subscales and the summary score of the UK IBDQ is demonstrated by Cronbach's alpha and item-total correlations. Their validity is demonstrated by their correlations with SF-36 subscales and an empirical index of disease activity. Good intraclass correlations and responsiveness ratios show their reproducibility and responsiveness. The findings support the reliability, validity, reproducibility, and responsiveness of the UK IBDQ and its acceptability to patients in UK.