The location of soft tissue sarcoma (STS) in the retroperitoneal space (about 15% of all STS) is a special therapeutic challenge, which is why these cancers should be strictly treated in specialised centres. The most common subtypes in this area are liposarcoma (mainly well-differentiated liposarcoma WD LPS and dedifferentiated liposarcoma DD LPS), leiomyosarcoma, and solitary fibrous tumour. The specificity of retroperitoneal sarcomas (RPS) is based on a high potential for local recurrence, less frequent occurrence of lung metastases (more often to the liver), and greater difficulty in achieving adequate tissue margins (extra compartmental locations, invasion of vital organs). The main prognostic factors include the size of the tumour, histological subtype, histological malignancy, multifocality, and radicalism of the resection. Nomograms can be used to assess the prognosis. Extensive resections that include the adjacent organs (kidney, intestine, muscles, liver) along with the tumour are the only way to cure these cancers and are particularly justified in cases where no macroscopic tumour fragments are left. When planning the treatment preoperative radiotherapy should be considered and also (in high-grade cases) chemotherapy based on doxorubicin and ifosfamide. During the surgery together with the tumour are often removed: kidneys/adrenal glands (in about 50% of patients), large intestine — right or left-sided hemicolectomy (over 20%), part of the pancreas (15%), and spleen (10%). Block resections of retroperitoneal STS together with infiltrated peripheral organs improves patients’ survival (especially in the case of liposarcoma). Some authors propose operating RPS in a “compartmental” manner, removing also the unoccupied surrounding organs, such as the spleen, pancreatic tail, kidney, and lumbar muscle, which may improve the patient outcome because microscopic infiltration of adjacent organs, which macroscopically are not occupied by sarcoma in over 60%. A liberal approach to resection of adjacent organs that are not involved by cancer should always be considered when the scope of surgical treatment is selected. The quality of the margins should be taken into account, as well as the histological type and the expected complications. Surgical complications after extensive MPZ operations concern about 12–15% of patients. Determination of infiltration of the inferior vena cava in the imaging tests requires special analysis because some of the operated cases of leiomyosarcoma may develop from its wall.