Simple SummaryThe treatment of retroperitoneal sarcomas poses significant challenges due to their infrequency, clinical and histologic heterogeneity, and unique anatomical location. We provide an updated review on the management of retroperitoneal sarcoma and issue clear and concise recommendations for the treatment of the main clinical situations encountered in this disease.AbstractSoft tissue sarcomas (STS) are an uncommon and biologically heterogeneous group of tumors arising from mesenchymal cells. The incidence is estimated at five cases per 100,000 people per year. Retroperitoneal sarcomas (RPS) account for 10–15% of all STS, and their management depends on their anatomical characteristics and histotype. Due to their very low incidence, it is recommended that RPS be treated in reference centers and evaluated by an experienced multidisciplinary team (MDT). In Spain, the Spanish Group for Research in Sarcomas (GEIS) brings together experts from various specialties to promote research on sarcomas and improve treatment results. This paper summarizes the GEIS recommendations for the diagnosis, treatment, and follow-up of patients with RPS.