peer reviewed ; In Wallonia, the zones of economic activities have been developing since just after the Second World War and have always contributed to both economic development and good regional planning. Originally reserved for large-scale industries of the fordist type, the formula was extended to include small and medium-sized companies, except retail business, and even generated specialised spaces like science parks, multi-modal transport centres and business parks. Throughout its development the success of the zones and the parks has scarcely weakened: there are over 200 in the region today in which over 4,500 companies can be found totalling over 20% of private employment in Wallonia. The companies present correspond to the large majority of the new industries and activities of the heavy service sector and also to a very large number of transfers of activities that were long ago located in the urban towns. Nevertheless, the recent expansion of zones raises an increasing number of questions: should their expansion be encouraged, or should it instead be slowed by more efficient management? This article studies these questions and suggests avenues for reflections and suggestions that cross the divide between the zones themselves and, more globally, the policies of planning and development. ; En Wallonie, les zones d'activités économiques ont été développées depuis le lendemain de la seconde guerre mondiale et ont toujours contribué à la fois au développement économique et au bon aménagement du territoire. Réservée au départ à l'accueil des grandes industries de type fordiste, la formule s'est élargie aux petites et moyennes entreprises à l'exception du commerce de détail et a même engendré des espaces spécialisés comme les parcs scientifiques, les plateformes multimodales et les parcs d'affaires. Tout au long de son développement le succès des zones et des parcs n'a guère faibli : la région en compte aujourd'hui plus de 200 où se retrouvent plus de 4 500 entreprises totalisant plus de 20 % de l'emploi privé ...