The case of a patient with postirradiation osteosarcoma is presented. The 
20-year-old female was diagnosed as having osteosarcoma by histological 
examination of an open biopsy specimen. She underwent surgery for pure 
dysgerminoma and received adjuvant postoperative radiotherapy, 40 Gy to the 
pelvis and 30 Gy to the para-aortic region, 11 years ago. This case satisfied 
the criteria for radiation-induced osteosarcoma proposed by Cahan et al. 
Radiation-induced osteosarcoma is rare, but the possibility of that must be 
borne in mind.