BACKGROUND: This study sought to determine if preoperative image‐guided intensity‐modulated radiotherapy (IG‐IMRT) can reduce morbidity, including wound complications, by minimizing dose to uninvolved tissues in adults with lower extremity soft tissue sarcoma. METHODS: The primary endpoint was the development of an acute wound complication (WC). IG‐IMRT was used to conform volumes to avoid normal tissues (skin flaps for wound closure, bone, or other uninvolved soft tissues). From July 2005 to June 2009, 70 adults were enrolled; 59 were evaluable for the primary endpoint. Median tumor size was 9.5 cm; 55 tumors (93%) were high‐grade and 58 (98%) were deep to fascia. RESULTS: Eighteen (30.5%) patients developed WCs. This was not statistically significantly different from the result of the National Cancer Institute of Canada SR2 trial (P = .2); however, primary closure technique was possible more often (55 of 59 patients 93.2% versus 50 of 70 patients 71.4%; P = .002), and secondary operations for WCs were somewhat reduced (6 of 18 patients 33% versus 13 of 30 patients 43%; P = .55). Moderate edema, skin, subcutaneous, and joint toxicity was present in 6 (11.1%), 1 (1.9%), 5 (9.3%), and 3 (5.6%) patients, respectively, but there were no bone fractures. Four local recurrences (6.8%, none near the flaps) occurred with median follow‐up of 49 months. CONCLUSIONS: The 30.5% incidence of WCs was numerically lower than the 43% risk derived from the National Cancer Institute of Canada SR2 trial, but did not reach statistical significance. Preoperative IG‐IMRT significantly diminished the need for tissue transfer. RT chronic morbidities and the need for subsequent secondary operations for WCs were lowered, although not significantly, whereas good limb function was maintained. Cancer 2013. © 2013 American Cancer Society. The results of this prospective trial indicate that image‐guided intensity‐modulated radiotherapy appears to reduce the risk and severity of wound complications by reducing dose to tissues required for wound closure following soft tissue sarcoma resection. Moreover, the dose to bone and unaffected musculature is also apparently reduced, leading to improved limb function measures with no bone fractures.