The efforts made to plan cities in emerging and developing countries are confronted to multiple issues, especially in small and middle-sized cities, which can be considered as poor through several criteria: socio-economic level of majority of population; low levels of public investments, weak quality of local administration, and large dependence of external donors. Following several authors, one of the main reason is that philosophy and methods of urban planning applied to these specific contexts are directly reproduced from a Western tradition, which does not correspond to the local and national context in terms of needs, priorities and organization of the financial resources. The case of Koudougou, a medium-sized city in one of the poorest countries in the world, Burkina Faso, with a population of 115.000 inhabitants, will give the opportunity to understand concretely which and how these deficiencies are translated in an African urban context. And foresee, more globally, alternative models of urban planning better adapted to medium-sized cities, focusing on the intermediation with their environment, in the perspective to offer new instruments of urban planning able to tackle in an efficient way the main constraints of their urbanization: growing population; territorial extension and fragmentation; environmental contamination and health; poverty and social exclusion, urban governance.