The aim is to evaluate the efficiency of the treatment with 153-samarium hydroxyapatite (153-Sm-HA) in haemophilic arthropathy. Thirty-one patients (30 males) with ages ranging from 8 to 34 years (average age = 20.6 years) were treated with fixed intra-articular dose of 185 MBq (5 mCi) and divided into two groups: infantile-juvenile (13 patients with up to 18 years of age, an average age of 12.7 years and arthropathy evolution of 7.8 years), and adult (18 patients older than 18 years, an average age of 24 years and arthropathy evolution of 18.7 years). The clinical evaluation before and after 1 year of synovectomy used the following criteria: subjective (pain through visual scale, articulation inspection), objective (articular movement through flexion level, sensitivity to palpation and leakage through joint circumference), reduction on the use of the coagulation factor, number of haemarthrosis, and the occurrence of adverse effects. The results were classified as: 1, good (remission from 70% to 100% of manifestations); 2, moderate (remission from 40% to 69%); and 3, poor (remission from 0% to 39%). Seventy-eight joints were tested: 15 knees, 36 elbows, 24 ankles, 1 shoulder and 2 hips. Early scintigraphic (1-2 h) and late scintigraphic (24-72 h) studies were performed after synoviorthesis. The cost of the procedure per joint was also estimated. No significant difference in the synoviorthesis result between groups was observed. The results were good for 75% of elbows, 87.5% of ankles and 40% of knees; the reduction in haemarthrosis and use of the coagulation factor was respectively 78% and 80% for elbows, 82% and 85% for ankles and 30% and 35% for knees. Four cases of reactional synovitis were observed in the 31 patients. The scintigraphic control showed homogeneous distribution of the material with no articular escape. The use of 153 Sm-HA in the treatment of the haemophilic arthropathy is effective for intermediate-size joints (elbows and ankles), but less effective for knees. Moreover, this treatment presents an excellent safety profile and accessible cost.