Five patients severely affected by haemophilia, in whom six knees showed advanced haemophilic arthropathy, have been studied. The patients presented with painful limitation of movement and increasingly frequent episodes of spontaneous bleeding in the affected knees. These all showed secondary degenerative changes and varus deformity. A Corrective osteotomy of the proximal tibia was performed under full haematological cover without complications. Follow-up ranged from 6 to 36 months, with a mean of 18 months. At follow-up all patients were free of pain and had retained their range of movement. In the three patients with a longer follow-up there was radiological improvement. The most significant feature was that there was almost complete cessation of bleeding episodes into the knee in all patients and no progression of the arthropathy. The cost benefit implications of this corrective procedure are discussed.