The afterloading technique for radiation therapy of gynaecologic malignancies has significant advantages for the patients as well as the medical staff: a reduced risk of perforating the uterus, more accurate treatment planning, a more agreeable treatment environment for the patients and, most importantly, a significant reduction of radiation exposure for the medical staff. Using simple ultrasound methods, the localisation and the extent of the tumour to be treated by radiation therapy can be assessed. With these data, the suitable isodose curves are selected. The distance to adjacent organs, especially of the loops of bowel next to the uterus which are normally not reached by dosimetric probes, can be estimated and the information included into treatment planning, thus reducing the risk of radiation side effects. Furthermore, the insertion of afterloading applicators and dosimetric probes can be checked by ultrasound making injury to the uterus and other organs less likely. At the same time, the correct position of the instruments is verified. For the ultrasonographic evaluation of the radiation response of primarily irradiated carcinomas more data are needed.