In this study Geographic Information Systems were used to investigate the relationship between forest habitats of mushrooms and the geology of an area. Mushrooms grow in different habitats, but the vast majority of them are strongly related with specific tree species. The study area is Grevena, a city in Greece with very rich fungal diversity and characteristic geology. GIS were used to produce thematic maps of Grevena prefecture based on data layers of elevation, geology, vegetation zones, land use and forests.A rough mapping of the fungal flora in the area in correlation to geological data indicates that certain mushrooms are more likely to be found in specific forest ecosystems, while certain forest types in the study area are related with specific geological formations. This paper aspires to be the basis of a more thorough and accurate mapping of the mushrooms’ habitats of the area.