The main focus of this paper is the question if the success of regional integration organisation in developing countries is, in fact, dependent on factors like similarity of their economic structure, market size or lack of committment. It is shown that there are also other more important institutional and politico-economical reasons to explain the functioning of such organisations in developing countries. Case studies of ECOWAS and SADC will be used to discuss this question. It is also very often argued that southsouth integration is inferior to north-south integration. This will be discussed considering the case of MERCOSUR as an example.