Use of Geant4 in CMS

GEANT4 is a detector simulation toolkit designed for the next generation of high energy physics experiments.It exploits advanced software engineering techniques and Object-Orientedtechnologies. A first use of GEANT4 has been made in the CMS Collaboration of the future LHC experiment at CERN, for the simulation of the highly complex detector structure. The detector construction is based on an external description of a mother-daughter volumes hierarchical logic. A graphical representation of CMS is shown, as well as some validation plots concerning the hadronic physics, based on the simulation of a hadronic calorimeter test-beam setup.