The use of geographical information systems (GIS) in a variety of application areas points to an increasing interest in the spatial aspects of health policies. Despite the fact that most public sector organisations in the United Kingdom (UK) have access to such software tools, there has not been a comprehensive review of take-up within the health sector. In this paper, we report on a recently completed mixed-method research project that has examined the current levels of GIS use in the UK National Health Service, and focus our discussion on health authorities (HAs). Couched within the context of previous studies that have been concerned with outlining the types of factors influencing IT implementation in the health sector, we illuminate the importance of behavioural, cultural and organisational factors on the diffusion of GIS in the UK National Health Service. It is noted that very few organisations had a GIS strategy and we contend that if GIS is to play a wider role in addressing issues surrounding 'joined-up' government, more advice and guidance is needed on policies promoting the exchange of geographical data between agencies concerned with tackling health issues. We conclude by drawing attention to the perceived lack of national guidance on GIS matters, more generally, within the UK health sector.