[en] From 1974 to 1983 in the Netherlands Cancer Institute, 21 patients with desmoid tumours were treated with radiation therapy. Nineteen patients were irradiated postoperatively (11 patients had micro- or macroscopic residual disease, 8 patients treated for recurrent disease had narrow surgical margins), 2 patients with inoperable tumours were treated with radiation alone. The entire involved muscle received a dose of 40 Gy, while a boost of 20 Gy was delivered to the tumour bed. Local control was achieved in 19 out of 21 patients, with an actuarial 5 year disease-free survival of 90%. No relation could be found between the amount of tumour present and local control. With careful set-up of treatment fields and long-term physical therapy, complications like fibrosis, ankylosis and oedema could be minimised. These excellent results with radiotherapy for minimal residual tumour, or even for macroscopic tumour, makes mutilating surgery unnecessary. (Auth.)