['Local recurrence (LR) is the primary cause of death in patients with retroperitoneal liposarcoma (RP-LPS). The purpose of this study was to evaluate if the addition of preoperative radiation therapy (XRT) to radical resection for RP-LPS at a single institution was associated with improved LR.', 'This retrospective analysis included patients with unifocal, primary RP-LPS who underwent complete R0/R1 resection at a single institution between 1991 and 2013. Multiple patient, tumor, and surgeon characteristics were tested to evaluate their association to LR (recurrence in the retroperitoneal space). We used competing risk hazards regression to evaluate the effect of preoperative XRT on the probability of LR.', 'There were 41 patients with liposarcoma histology whose tumors included entirely well-differentiated (N\u2009=\u200913), de-differentiated components (n\u2009=\u200926), myxoid (n\u2009=\u20091), and NOS (n\u2009=\u20091). Preoperative XRT was significantly associated with a lower probability of LR (HR 0.11, 95%CI 0.01-0.91, P\u2009=\u20090.04) and a higher 5-year local recurrence-free survival (95.6%, 95%CI 72.4-99.4%, vs. 75.0%, 95%CI 40.8-91.2%; P\u2009=\u20090.0213), but not with 5-year distant recurrence-free survival or disease-specific survival.'] Is preoperative radiation therapy combined with radical surgical resection associated with a lower rate of local recurrence when treating unifocal , primary retroperitoneal liposarcoma?