Making decisions in complex situations is extremely difficult. Short time for analysing aspects of the incident and the psychological pressure, make the case even worse. Conditions in which decisions are made are common for Rescue Services. In order to overcome these difficulties, a number of research projects have been initiated, all aimed at finding the best way of making decisions in emergency situations. This article describes Decision Support System (DSS) for the National Fire Service of Poland. The system is based on Directory Services and Case-based Reasoning techniques. Section 2 contains Case-based Reasoning technique principles. Section 3 contains basic information about the Directory Service. In section 4, description of the proposed Decision Support System is included. Conclusions are contained in the summary at the end of the paper.