The objective of the paper is to present the development of a real estate evaluation system with the use of GIS (Geographic Information Systems) technology. System (REGIS Real estate Evaluation Geographic Information System) was developed with MS Visual Basic 6.0. and Map Xtreme 4.5. (Graphical User Interface), also User Interface was developed on GIS platform (MapInfo Professional 6.5.) and the database in Microsoft Access 2000 (DBMS) during the PhD thesis of one of the authors. The system focuses on the evaluation of the real estate property values. Valuation methods that are used by the system can be grouped as traditional and advanced. The traditional methods are regression models and comparable method. The advanced methods are ANNs (Artificial Neural Networks), spatial analysis methods and fuzzy logic. The real estate model is built on a regional data bank of some owner-occupied or non - owner-occupied residential properties sold in specific time. These properties are located using geodetic co-ordinates. They are integrated into software of GIS. Many attributes are available to describe this real estate model. Also all methods that are used by the system depend on property variables. They can be grouped as follows: Environmental variables (neighbourhood, distance or proximity, and social - economic variables), Financial variables, and Property variables (quantitative and qualitative variables of the property). Some of the variables can be measured while others cannot. Variables quantification may become easier through GIS tools (buffering, overlay and modelling). The applicability of the system was tested with a case study in estimation of house sales prices. It was used in order to evaluate property values in one municipality of Attica in Greece. The estimation, market analysis, forecasting and management of property values are of great importance and prerequisite for real estate development.