Retroperitoneal sarcomas are rare neoplasms. CT or MR imaging is performed in patients with these tumors to detect local extent and distant metastases of the tumor and for preoperative surgical planning. Most sarcomas cannot be characterised as to cell type with CT or MR, with the exceptions being liposarcomas and intracaval leiomyosarcomas. Similarly histological grading cannot be made definitively with imaging alone, the exception being liposarcoma since well differentiated liposarcomas contain more macroscopic fat than do less differentiated liposarcomas. After surgery, follow up imaging with CT or MR and careful scrutiny of the tumor bed and resection site are essential to detect early recurrences, which can often be managed with re-resection.