Well differentiated soft tissue sarcomas may benefit from fast neutron radiotherapy, in particular inoperable and recurrent tumors and tumors with residual disease after non-radical surgery. Treatment planning in a multidisciplinary pretherapeutic approach has to be based on tumor size and site and histopathology. Target volume definitions for potential microscopic spread and for the high risk region of local recurrence have to consider the preoperative tumor localization (imaging), the biological behavior and the extent of surgery. GI/II, T1-3 tumors after intralesional or marginal resection are indications for neutron therapy. Treatment planning and delivery has to take into account the narrow therapeutic range of fast neutrons and include individual immobilization devices, manufacturing of bolus and CT based computed dose calculations. Neutron radiotherapy techniques at the d, T generator are comparable to photon techniques except individual beam shaping, field size and portal verification. Total dose is 16 Gy neutrons in the high risk region and 12 to 13 Gy in the region of potential microscopic spread.