The uneven spatial distribution of basic facilities within urban areas is a major problem for developing countries like Senegal due to the emphasis of accessibility disparities and the use of this services. The efforts to quantify the problem and its consequences on people are constrained by the lack of satisfactory data and methods. The study seeks to examine the spatial accessibility to basic services (access to water, health, education, economic infrastructure and transportation services) in a very heterogeneous urban system and to highlight inequalities in access for improving the geographical accessibility and to ensure equity. The article explore the use of spatial analysis method (Closest Facility) to measure the potential accessibility to services and facilities in the city of Mbour. The analyses uses all the inhabited houses of the city as the potential demand. Results emphasis unequal access to basic urban services in the city and a center-periphery model with a high concentration of services around the city. The study demonstrates the utility of this method for the identification of disadvantaged areas, decision making and planning of basic services. It also provides paths for improving accessibility in urban areas with a high density of population.