Aims: This paper describes two contrasting cases of post-radiotherapy angiosarcomas of the breast. They illustrate the spectrum of malignant vascular tumours that may occur in the breast. These tumours are extremely rare and knowledge of their natural history is limited. The prognosis suggested by the few published cases of poorly or moderately differentiated angiosarcomas suggest a poor prognosis often with a fatal outcome. Methods and results: This was confirmed by our first case a poorly differentiated angiosarcoma, occurring 10 years after radiotherapy for breast carcinoma with death occurring from metastatic angiosarcoma 6 months later. Our second, more recently diagnosed case, was a well-differentiated angiosarcoma, occurring 5 years post radiotherapy for breast cancer. She remains well 12 months after the diagnosis of sarcoma but her long-term outlook is more problematic to predict. Only five previous cases of well-differentiated post-radiotherapy angiosarcoma of the breast have been reported with limited follow-up (average 2 years). Conclusions: Communication with the authors of four of the papers since their publication has provided valuable additional information and indicates a potentially good outlook for this woman in the longer term. A second cellular component was also found in these malignant vascular tumours. These spindle cells distinct from the malignant endothelial cells have not to our knowledge been described previously and their possible nature is discussed.