Integration of health-related inputs into a geographic information system (GIS) creates a powerful tool for assessing and optimizing health care systems.  A health GIS has been developed for the Republic of Yemen to allow national- and governorate-level health officials to visualize, understand, and make decisions more easily.  The GIS includes base data and census information collected from the Yemen Central Statistical Organization (CSO) and the Social Fund for Development combined with best available health indicators and statistics collected from the Ministry of Population and Health.  Detailed health facility survey data are being collected by CSO and will be supplemented with digital photographs of exterior and interior conditions for health facilities in specified areas.  Integration of these data into a relational database with a GIS interface facilitates efficient use of limited resources for improving health care in the predominately rural country of Yemen.  Five state-of-the-art health GIS applications for Yemen are described, which include: (1) mapping health facilities and analyzing accessibility areas; (2) using GIS to target health care program interventions; (3) illustrating health statistics; (4) plotting the spatial pattern of the 2000 Rift Valley Fever outbreak; and (5) integrating health indicators into a customized query, analysis, and reporting database management tool linked directly to the GIS.  These GIS applications demonstrate sophisticated use of health information to enhance facility utilization, improve distribution of preventive and curative care, and provide evidence-based rationale for targeted assistance and service delivery.  Additionally, the Yemen health GIS may advance decentralization of selected aspects of decision-making and health reform authority.