Magnetic Resonance Imaging (MRI) is the cornerstone imaging modality in the management of soft tissue sarcoma (STS), offering a detailed assessment of both anatomical and functional aspects that are critical for accurate diagnosis, tumor biopsy guidance, and surgical planning aimed at achieving wide-margin resections. This chapter focuses on the essential role of MRI in postoperative evaluation, particularly its ability to distinguish normal postoperative changes from tumor recurrence using a combination of conventional and advanced imaging techniques. The concept of surgical margins from a radiological perspective will be discussed, as well as the patterns of local recurrence, and the diagnostic accuracy of MRI in identifying residual or recurrent disease. Additionally, the chapter reviews the distinctive imaging features of recurrent or residual tumors and the challenges in distinguishing these from postoperative inflammatory changes. Finally, the chapter outlines follow-up guidelines, emphasizing the critical role of MRI in the multidisciplinary management of STS and its impact on patient survival.