The problems associated with planning and managing patient treatment through complex care settings are significant. It has long been realised that support tools are invaluable in ensuring quality and consistency of care in a domain characterised by complex information spread over widely differing contexts. This paper focuses on the temporal nature of medical support tools and describes structures designed to accommodate their representation and reasoning requirements. The paper discusses the temporal facilities of the CIG-Plan medical care planning system and critically compares our work with contemporary research in the medical guideline and AI Planning communities.