Heath related quality of life has been an important object of interest in the clinical practice, focused on assessment of treatment effects from patient's point of view, with particular emphasis placed on effect of treatment on daily patient functioning. Concept of health-related quality of life needs valid and reliable instruments.The aim of the study was to present the process of validation of a new version of EORTC QLQ-CR29 module in Polish patients suffering from rectal cancer.Material and methods. EORTC QLQ-CR29 module comprises 29 questions, and was adapted to Polish cultural conditions based on EORTC procedure. Data collected from 20 patients were analyzed, their agreement with theoretical and empirical structure was assessed. Convergent and discriminant validity were analyzed with multi trait scaling.Reliability was assessed with Cronbach alpha coefficient. Known group validity was assessed in terms of differences between men and women, and between stoma and non-stoma patients. Exact Mann-Whitney test was used. P values lower than 0.05 were considered significant.Results. Scales built on bases of empirical model of module had higher validity and reliability than those based on theoretical model.There were no significant differences between men and women in health-related quality of life. Significantly higher values were observed in non-stoma patients on body image scale and for leakage of stool item. Reversed relationship was observed in case of abdominal and buttocks pain, as well as embarrassment because of bowel movements.Conclusions. Module CR29 is a valid and reliable tool, which enables standardized measurement of treatment effects, suggested for use as main tool measuring impact of disease itself and applied treatment on health-related quality of life of rectal cancer patients.