Engineering-Procurement-Constru;ction business fields, usually called EPC, are the fields that could not be separated from the strategic industrial business sector. PT. WDJ is one of the companies that have been dealing in EPC for more than 20 years. The implementation of Information Technology (IT) at PT. WDJ has not covered all existing business processes and has not been integrated yet. It indicates that there is a big potential in utilizing and developing IT as one solution for improving and increasing the efficiency of company's business processes. To know furthermore how IT can take a role in the improvement of business process and increase its efficiency, this research took the procurrement business process, which is one of the core businesses of PT. WDJ, as a case study. The phases in this research generally adopted from the Davenport and Short business process improvement framework. ProVision ver 4.2 Enterprise Pro from Proforma Corp. is used as a tool for business process modeling and simulation. Client/ server application, decision support system, document workflow management and electronic authorization system are some results of IT development that can be found nowadays. By using these IT development results for improving the procurement business process, it can be seen that there is an increasing in time efficiency about 40.95 % and cost efficiency about 35.75%. The increasing of efficiencies indicates that there is an increasing in the performance of procurement business process.