The marketing decision support system is designed to help marketing managers in the analysis and decision making processes. The magnitude of a consumer market is measured by its economic, demographic and geographic dimensions. From this point of view, we focused on demographic and economic factors, which exist within macro environment factors in this study. The purpose of this paper is to point out the importance of consumption maps such as food, education, health expenses etc. which provide significant cues for investors and marketers especially in determining optimum locations. In this context, all data was integrated on Geographical Information Systems (GIS) environment. In addition, user interface programs were developed to perform easily several queries and analyses in ArcGIS 9.3 GIS Software. Afterwards, the data was queried, analyzed and documented by GIS. Finally, related consumption and optimum location maps for the marketing were produced. This study shows that GIS can play significant roles in both marketing planning and the decision making process. Consequently, new marketing strategies can be determined by means of recommendations resulted from this study in the city of Sivas and other cities. (C) 2014 Elsevier Ltd.