Synovial sarcoma is a rare malignant soft tissue tumor. The histological diagnosis remains sometimes difficult. The authors report 46 cases, treated in different hospitals in Paris. The medium survival rate of this group (which includes cases treated long ago) is of 30 per cent at 5 years. But only 24 per cent are disease free at this time. At the last follow up, the patients deceased after the fifth year included, the survival rate drops down to 12 per cent. Local recurrences and metastasis are analysed with reference to the different treatments applied. It seems that the association of polychimiotherapy and wide surgical excision might increase the survival rate, but this has to be confirmed in future. Radiotherapy is still a valuable treatment when excision is only limited, or when excision is impossible, due to localisation or extension of the tumor.