The article presents an analysis of 107 cases of simultaneous operations of big volume with main stage as gastric resections (gastrectomy) or large intestine resections and mean volume interferences as cholecystectomy and removal of abdominal hernias. It was stated, that simultaneous operations compared with two steps treatment of combined surgical diseases obtained the high economical efficacy. This efficacy was determined by a single - stage routine presurgical examination, single anesthetic management, less medical expenses for medication and laboratory - instrumental studies in postoperative period, significant shortening the terms of hospitalization and disability terms. The authors proposed formulas to evaluate the economiс efficacy of simultaneous operations in system of paid medical service and system of rendering medical aid using paid medical insurance. The efficacy of large operations was 40 766 rubles and in case of mean volume interventions - 25 382 rubles for the paid medical system. The economical efficacy of simultaneous operations of large and mean volume was the same in the system of obligatory medical insurance. It consisted of 19 737,5 or 22 920,1 rubles and depended on the degree of operative anaesthetic risk of the second intervention in two steps treatment of patients.