The surgical operation is a principal and in most cases a solitary treatment for non-organ retroperitoneal tumors. High risk of recurrence, aptitude to large local extension dictates necessity of individual surgical plan. An equality of approach is excluded. Pre-operative specified diagnostics of tumor extension is extremely important. We present an experience of determination of such characteristics of non-organ retroperitoneal tumors, which influence the size of surgery (plurality of lesions, invasion of adjacent vessels and organs).