Purpose of the study. The aim of the work was to optimize the prognosis of recurrences of retroperitoneal extraorgan liposarcomas of various degrees of differentiation by detecting microRNAs (miRNAs) of tumor cells with differential expression depending on the course of the malignant disease.Materials and methods. The study was conducted on 96 patients: 19 patients with lipomas and 77 patients with retroperitoneal extraorgan liposarcomas. Tissue samples were obtained during the operation. Among patients with malignant diseases, highly differentiated liposarcoma (VDLS) was detected in 51 patients, and dedifferentiated (DDLS) in 26 patients. miRNA expression levels in tumor cells were determined using real-time PCR.Results. During the follow-up period, relapses of malignant disease were detected in 25 (32,5%) people: 13 (25,5%) among patients with VDLS and 12 (46,2%) among patients with DDLS. In DDLS, characterized by a more aggressive course, there was an increased level of expression of miRNA155, -21, -26a2 and a decrease in expression of miRNA15a and -34 compared with patients with VDLS. In patients with recurrent retroperitoneal liposarcomas, the expression of miRNA15a was initially 83% lower in tumor cells of surgical samples (p<0,001), iRNA34 by 79% (p< 0,001), and the expression activity of miRNA155 was 7,54 times higher (p<0,001) and miRNA26a2 by 6,93 times (p<0,001).Conclusion. The determination of the expression of miRNA155, -26a2, -34, -15a in tumor cells during surgical treatment of patients with retroperitoneal liposarcomas is an effective way to assess the risk of recurrence and is relevant for determining the tactics of further treatment of patients.