This paper explores the possibilities of using GIS for private hospitals at Jeddah city, Saudi Arabia. A GIS application is created to cover three main health planning issues which are distribution of health demand, classification of hospital patients and the definition of hospital service area. Each one of these issues is covered using several GIS functions including network analysis and overlay analysis. The former is used to produce drive-time hospital service area and the latter is applied at the selected hospital to calculate the size of its served demand. GIS has several useful functions and tools that can be used in health planning field. This paper uses some of these functions for one private hospital. These functions are used to help health planners on evaluating the spatial distribution of hospital demand and for defining hospital service area. All the produced models can be applied on any private or public hospital in Jeddah city. They can be used to build a spatial decision support system for hospitals in Jeddah city.