Fuzzy models to assist with real estate appraisals are described and previous experiments on optimizing them with evolutionary algorithms implemented in MATLAB are summarized. An approach was made to use the KEEL Tool, developed in Java by a group of Spanish research centres, to investigate the models. Five fuzzy models comprising 3 or 4 input variables referring to the attributes of a property were learned and evaluated using six regression algorithms for fuzzy rule based systems implemented in the KEEL Tool. The experiments were conducted using a data set prepared on the basis of actual 134 sales transactions made in one of Polish cities and located in a residential section. The results were encouraging. The KEEL Tool has proved to be very useful and effective research tool, especially thanks to its 10-fold cross validation mechanism and relatively short time of data processing.