The indication for a synoviorthesis (medical synovectomy) is chronic haemophilic synovitis causing recurrent haemarthroses, unresponsive to haematological treatment. Synoviorthesis is the intra-articular injection of a certain material to diminish the degree of synovial hypertrophy, decreasing the number and frequency of haemarthroses. There are two basic types of synoviorthesis: chemical synoviorthesis and radiation synoviorthesis. On average, the efficacy of the procedure ranges from 76 to 80%, and can be performed at any age. The procedure slows the cartilaginous damage which intra-articular blood tends to produce in the long term. Synoviorthesis can be repeated up to three times with 3-month intervals if radioactive materials are used (Yttrium-90 and Phosphorus-32), or weekly up to 10-15 times if rifampicin (chemical synovectomy) is used. After 30 years of using radiation synovectomy worldwide, no damage has been reported in relation to the radioactive materials. Radiation synovectomy is currently the preferred procedure when radioactive materials are available, however, rifampicin is an effective alternative method if radioactive materials are not available. Several joints can be injected in a single session, although no more than two joints at the same time is probably the best protocol to follow.