Анотация: Osteoarthritis is a degenerative process which involves different structures of the synovial joints. Degradation and repair of the articular cartilage - the most important involved structure - were investigated by measuring interleukin (IL) 1 beta and IL-6, joint markers of degradation and repair respectively. To this end, five mature large size mixed-breed male dogs were used for this study. Synovial fluid samples were obtained from joints by aseptic arthrocentesis before surgical sectioning of cranial cruciate ligament (CCL) and on days 14, 28, 90 and 180 after CCL transaction. Statistical analysis of the results showed that both cytokines exhibited an increasing pattern. IL-1 beta showed significant increase after six months and IL-6 showed a non-significant increase. There was no significant correlation between these cytokines during the study. We concluded that although both degradation and repair were in progress in osteoarthritic joints, degradation was predominant over repair when no treatment was performed to slow down the process