Surgery is the mainstay of therapy for primary, non-metastatic, retroperitoneal sarcomas. However, even after curative intent surgery, local recurrence rates are high and can lead to significant morbidity and mortality. The utility of neoadjuvant radiation therapy has been debated, although most published data has been from retrospective studies. The recent publication of the STRASS trial represents the first completed, multi-center, prospective, randomized controlled trial of neoadjuvant radiation plus surgery versus surgery alone. In this article, we review the importance of local control for retroperitoneal sarcomas, summarize the findings of the published data, highlighting the STRASS trial, and review the potential toxicities of retroperitoneal radiation therapy. Although the STRASS trial is largely considered a negative trial, it highlights key themes in understanding the biology of various histologic subtypes and potential areas for further study.