Retroperitoneal sarcomas are rare malignant tumors, which are developing from mesenchymal stem cells residing in muscle, fat, and connective tissues. Underlying the rarity of this kind of tumors in general population, the aim of this paper is to present three cases of retroperitoneal sarcomas operated in Surgical Department of Military Hospital of Craiova (a retroperitoneal liposarcoma, a dedifferentiated liposarcoma and a malignant fibrous histiocytoma). From clinical point of view, we note the poverty of symptoms and non-specificity of these and a great tolerability of retroperitoneal space that offers the possibility for a great development of the tumor. CT-scan and MRI are the best investigations for diagnosis but surgical exploration is the best way for a good evaluation of these tumors. From histological point of view, we try to present new features about these kinds of tumors in order to classify them. Results of surgery correlated with complementary therapies were good without per-operative mortality or postoperative morbidity but we noted a recidive of one tumor (with different histological pattern) 21 months after the surgical intervention. The rarity of retroperitoneal sarcomas, combined with the vast array of histologic subtypes, has complicated our understanding of these tumors and impeded the development of effective therapies.