Multiple primary malignant neoplasms are not uncommon, whereas 2 different types of primary sarcomas simultaneously presenting in 1 individual is quite unusual. We encountered a patient presenting with a uterine sarcoma and another retroperitoneal mass at the same time. These 2 tumors showed distinct pathologic and immunohistochemical features. The diagnosis of a synchronous presentation of a uterine leiomyosarcoma and a retroperitoneal sclerosing well-differentiated liposarcoma was rendered. Further study by comparative genomic hybridization showed unrelated genomic alterations of these 2 tumors. Nevertheless, other common genetic alterations such as balanced translocations, point mutations, or epigenetic modifications could still exist because of the limitation of findings by comparative genomic hybridization. In conclusion, both metastasis and multiple primary tumors should always be taken into consideration in differential diagnosis while encountering synchronous sarcomas.