This chapter highlights the application of interoperative electron radiation therapy (IOERT) and brachytherapy in the management of extremity soft tissue sarcomas. It highlights how IOERT allows targeted radiation therapy to high-risk areas, thereby improving local control and potentially reducing late toxicity while preserving limb function. The chapter also explores the practical considerations for implementing IOERT and brachytherapy, including the coordination between surgical and radiation oncology teams and the technical aspects of radiation delivery. Additionally, it reviews the literature supporting these therapies, emphasizing their benefits in terms of local control, limb preservation, and functional outcomes despite potential risks in toxicity.