Since 2001 we have performed 105 radioisotope synovectomy (RS) in 65 children and young adults, age ranging from 3 to 25 years with a average of 15 years in Ege University Hospital, Izmir, Turkey. One fourth of cases were below 10 years of age. All patients had severe haemophilia A and B. Ten patients (17 joints) had high responder inhibitor. We prefer to use Yttrium 90 for all joints (5 mCi for knees; 2 mCi for others). The knees were injected in 56 cases, elbows in 24 cases, ankles in 23 cases and shoulders in two cases. Steroid injections were not preferred as the principle drug of choice. Mean follow-up period after procedure was 2 years (range: 6 months to 3.5 years). All inhibitor patients had satisfactory results. The best results were obtained in elbows than knees and ankles. Excellent rates (no bleeding) were observed in grade-II synovitis 84% for knees, 93% for elbows and 50% for ankles. Because of the excellent and good response (bleeding reduction to 75%), rates were 100% for knees and elbows and 92% for ankles. In six cases, repeated injections were given at 6-month interval and all of them had good results. The grading of synovitis seems to be an important parameter than the age of the patient. Even in patients below 10 years of age, outcomes are not satisfactory in all joints with grade-III vs. grade-II synovitis (12% vs. 73%). No serious complications were observed during and after procedure except two cases. A mild and transient inflammatory reaction was observed in the ankle. There was a minimal radioisotope leakage to superficial skin in the elbow. RS seems to be a safe and effective treatment for chronic synovitis causing recurrent joint bleedings.