Hemangioma of the synovial membrane is encountered in young adults in the form of a palpable articular tumour. The muscle wasting in the quadriceps is out of proportion with the clinical signs and should lead one to suspect the diagnosis. Lengthening of the limb on the side of the lesion by arterio-venous shunt is not rare. Histologically, hemangioma is a vascular tumour and there is the same difficulty in classification as for all vascular tumours. Synovectomy removing the tumour is the operation of choice. Relapse is possible leading to total removal of the synovial membrane. Complementary radiotherapy does not have a clearly defined place in treatment.