Introduction. Osteoarthritis is a degenerative rheumatic disease of the peripheral joints. It mostly affects one joint, usually the hip and knee joints, as well as the distal interphalangeal joints of the wrist and thumb carpometacarpal joint. The clinical symptoms include pain, swelling, stiffness, crepitus, muscle atrophy, subluxation, as well as reduced joint mobility, greatly affecting the quality of life of patients. The aim of this study was to assess the quality of life of patients with knee osteoarthritis and determine whether there is a difference in the quality of life of patients with unilateral and patients with bilateral knee osteoarthritis. Material and Methods. The study was designed as a retrospective study including 60 patients, 30 patients with unilateral gonarthrosis and 30 patients with bilateral gonarthrosis. The EuroQoL five dimensions questionnaire was used to assess the quality of life. Results. There is no statistically significant difference in the quality of life between individuals with unilateral and bilateral knee osteoarthritis, but there is a significant positive correlation between the pain intensity and difficulties in the domains of quality of life. Conclusion. People with osteoarthritis of the knee mostly take painkillers and have a good or excellent response to therapy. There is no statistically significant difference in the quality of life among people with unilateral and bilateral knee osteoarthritis. There is a significant positive correlation between the pain intensity and difficulties in the domains of quality of life. There is a significant negative correlation between the perception of general health and all five domains of quality of life.