Radiation synovectomy is a safe and effective treatment for chronic haemophilic synovitis causing recurrent haemarthroses. This study reports results of 29 188Re-sulfide radiation synovectomies in knee joint with a follow-up 18 months. Using the absorbed dose factor, three groups of radioactivity dose (555 MBq, 687 MBq and 917 MBq) were used according to the synovium thickness that measured by MRI. Excellent and good results (haemarthrosis reduction from 75 to 100%) were obtained in 71% of cases at 18 months. Comparison of the results, no significant difference was found among the radioactivity dose groups. Radiation was well contained within the knee. There were no observed or identified complications including the detectable harm to the articular cartilage, as shown by MRI.