Background/Aim. Osteoarthritis (OA) is the clinical manifestation of degenerative joint changes. The aim of this study was to investigate differences in quality of life (QoL) between patients with severe hip and knee OA. Methods. This is the cross-sectional study of 195 patients (average age 63.2 ± 11.1 yrs), with a diagnosis of OA of the hip and knee that were assigned to receive a total hip or knee replacement. The patients were divided into three groups in relation to localization of OA. The first group included patients with hip OA; the second group consisted of patients with knee OA and the third group with both hip and knee OA. Demographic and clinical data were collected for each patient. We measured health related quality of life (QoL) by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires. Statistical significance of differences was at the level of p < 0.05. Results. The best QoL was in the group of knee OA (42.7 ± 11.3) and the worst in the group with both hip and knee OA patients (35.8 ± 12.7). QoL assessed by WOMAC score and the domain of physical function were significantly different among three groups of patients with OA (F = 5.377, p < 0.01 and F = 5.273, p < 0.01) respectively). Results of three multiple linear regression models where WOMAC score was dependent variable and age, body mass index (BMI), social class, pain, stiffness, physical function, hypertension, cardiomyopathy, diabetes mellitus were independent variables, have shown that QoL was statistically significantly associated with pain and physical function in the hip and knee OA groups, whereas in the group with both hip and knee OA patients, QoL was associated with BMI, pain, physical function and diabetes mellitus. Conclusion. QoL of patients with severe hip and knee osteoarthritis in relation to localization was significantly different. QoL in severe hip and knee OA patients was significantly associated with pain and physical function, but in patients with both hip and knee OA QoL was also associated with BMI and diabetes mellitus.