Schwannoma - a tumor growing from Schwann cells of the peripheral nerve sheath. Retroperitoneal schwannoma is a rare tumor accounting for approximately 1 to 5% of all retroperitoneal neoplasms. Retroperitoneal localization occurs for a total in 0.75-2.6% of cases, often they localize in the extremi- ties, the head and neck. Despite the significant progress made currently in the field of instrumental studies for non-organ retroperitoneal tumors, diagnosis and differential diagnosis remain a complex problem requiring further study. Presented clinical case illustrates difficulties in the diagnosis of retro- peritoneal schwannoma. Precise preoperative determination of the tumor relationship with all the nearby organs and vessels according to the different methods of ray diagnostics gives an opportunity to define the tactics of treatment.