There is much potential for the use of geographical information systems (GIS) within the management and analysis of health and health care data. This paper addresses the problems of using routine data in the creation of geographical information systems for health. The numerous sources of British official routine health information however vary greatly in their geographical coverage and geographical detail. Particular attention therefore focuses upon the extent to which existing data sets can readily be used within GIS. Recommendations for changes in the data collection process are forwarded to improve the potential for GIS use. The overall utility of geographical health information systems within health service planning is illustrated using the example of community based activities.