This study examines the Energy-Economy-Environment (3-E) interaction ingeneral and the rebound-effect in particular. The rebound-effect can be defined as that part of the initially expected energy savings, resulting from energy efficiency improvements, that is lost because of the 3-E interaction. To estimate the magnitude of this rebound-effect, the MARKAL-MACRO model has been used. MARKAL-MACRO is an integrated computer model, which is created by coupling the systems engineering model MARKAL and the macro-economic growth model MACRO.