An interesting issue is a hemodialysis patients' and renal transplant recipients'subjective assessment of their QOL as a basic sociological criterion of treatment efficacy. The aim ofthe study is an estimation and comparison of QOL between these patients with a questionnaire the WHOQOL-100as a trial of objective comparison of quality of life between these two groups of patients. A methodof diagnostic probing with use of the questionnaire in its Polish language version was employed. A numberof 400 (in total) questionnaires (200 in each group) were given to randomly chosen CRF patients. Fulfilledquestionnaires were obtained from 144 (36%) patients who underwent the study: 61 from HD group (30.5%)and 83 from TX group (41.5%). RESULTS: Regarding sex and education, differences between groups were notsignificant statistically. As for the age and marital status, differences between groups were significant(p = 2.5 E-13 and p = 0.0045 respectively). In the both groups, (living from the health pension fromthe Government Health Insurance--ZUS) was overwhelming (HD--96.12% and TX--77.11%). A difference in amountof 'having a job' patients between groups was not significant (p = 0.153). In QOL estimation, significantdifferences between group HD and TX were assessed in overall QOL (p = 1.04 E-07), in physical domain(p = 0.00053) and social relationships domain (p = 0.0004). In the rest of domains, scores were approximatein both groups and did not differ significantly. Comparing facets scores, some significant differencesbetween HD and TX groups were observed: pain and discomfort (p = 0.032), energy and fatigue (p = 2.2E-05), positive feelings (p = 0.002), body image and appearance (p = 0.010), mobility (p = 0.031), activitiesof daily living (p = 0.036), working capacity (p = 0.008), personal relationships (p = 0.004), sexualactivity (p = 7.3 E-06) and transport (p = 0.036). Higher scores were stated in TX group in all of thosefacets excluding body image and appearance and pain and discomfort. CONCLUSIONS: 1) TX patients QOL isbetter than HD patients' in domains: overall, physical, social relationships and environment and alsoin facets: pain and discomfort, energy and fatigue, positive feelings, mobility, activities of dailyliving, working capacity, personal relationships, sexual activity and transport. 2) In the facet bodyimage and appearance, TX patients' QOL is worse than HD patients'. 3) The results point out the WHOQOL-100to be a useful and reliable instrument for measuring quality of life in different populations makingpossible to compare it objectively.