Purpose: The main goal of treatment of soft-tissue sarcomas is achieving wide negative margins to improve local control and prevent recurrence. The role of radiation therapy (RT) is well established in sarcomas of the extremities; however, its role in unplanned surgery of soft-tissue sarcoma (when a mass presumed to be benign is resected and the pathology comes back as sarcoma, usually referred to as an “oops” operation) is inconclusive. This article reports on the effect of RT after an unplanned surgery before the reresection. Methods and Materials: A total of 65 patients who had undergone an unplanned resection of a postoperatively diagnosed soft-tissue sarcoma were treated with RT and/or surgery and retrospectively evaluated for disease progression. Treatment started with RT in 49 cases (75.4%), including 8 cases of no further surgery. A repeat wide resection was performed directly after the initial surgery in 16 patients, followed by RT in 15 of them. Results: The disease recurred in 7 out of 49 patients (14.3%) who received RT first and in 9 out of 16 (56.25%) who underwent reoperation before RT (P =.001). Disease-free progression was higher in cases of low-grade malignancy (P =.049). A clinical diagnosis of lipoma was associated with a better outcome than a diagnosis of nonlipoma (P =.034). The presence of residual tumor at reoperation did not affect disease control. Patient age, time between symptom onset and diagnosis, hospital level of initial diagnosis (tertiary versus nontertiary), anatomic site, tumor size, and margin status at the initial excisional biopsy were not significantly correlated with the outcome. Conclusion: Initiating treatment with RT followed by unplanned “oops” resection of soft-tissue sarcoma before the reresection improved disease-free survival as opposed to vice versa.