To a greater or lesser extent, all historians make use of geographical information. This means that there is clearly a large potential for the use of Geographical Information Systems (GIS) in the discipline. GIS has its origins in the earth sciences and its approach and the way that it models the world is based on the traditions and requirements of these subjects. This means that while there are many advantages to using GIS in historical research, its use must be implemented with caution, based on the limitations of the data and the traditions of historical scholarship. In this paper we define GIS and explain why it is relevant to historical research. We then use a wide variety of examples to illustrate the ways in which historians have used GIS. Finally, we discuss how GIS needs to be improved to make it more applicable to historical research. Our aim is to demonstrate that GIS, if properly used, is not only applicable to the more quantitative, scientific historical paradigms, but is equally appropriate in the more humanities-driven, qualitative areas of the discipline.