The therapy of recurrent knee joint effusions of patients with rheumatoid arthritis (RA) and spondyloarthropaties (Spa) is still the challenge for rheumatologists. Chemical synoviorthesis and radiosynoviorthesis belong to therapeutic method of proven efficacy. In this study we assessed the effectiveness of this two therapeutic procedures in treatment of patients with RA and Spa with recurrent knee joint effusions. We estimated the impact of two different types of synoviorthesis on the level of chosen indicators of systemic inflammatory process: CRP and fibrinogen. 16 patients (18 knees) with rheumatoid arthritis and 4 patients (7 knees) with spondyloarthropathies treated with chemical synoviorthesis and 16 patients (17 knees) with rheumatoid arthritis and 3 patients with spondyloarthropaties (6 knees) treated with radiosynoviorthesis were evaluated. During 6 months of observation the knee effusion relapse appeared in 10 knees among patients with rheumatoid arthritis (56% treated joints) and in 6 with 7 treated joints among patients treated due to spondyloarthropaties (86% treated joints) after chemical synoviorthesis. The recurrence of knee effusion after radiosynoviorthesis concerned 4 patients’ knees with rheumatoid arthritis (24% treated joints). The patients’ knees with spondyloarthropaties after radiosynoviorthesis were free of effusion during the time of observation. The level of CRP and fibrinogen increased clinically significant after 48 hours of chemical synoviorthesis. This phenomenon was not seen after radiosynoviorthesis. After 4 and 24 weeks of chemical and radiosynoviorthesis clinically significant decrease of the level of CRP was observed. According to our initial research we conclude that radiosynoviorthesis is more successful medical procedure than chemical synoviorthesis in treatment of recurrent knee joints effusions.