The aim of this paper is to present the method of reengineering of business processes that perform engineer-to-order production in a manufacturing company. The base of the method is a strategy of the company that applies Balanced Scorecard techniąue. The reengineering of critical business processes in the enterprise is assigned to the implementation of Enterprise Resource Planning system. The method facilitates the quantitative evaluation of business process improvements in the enterprise and the support for assigning the Total Cost of Ownership of the ERP system.