Introduction: Compton Cameras (CCs) are gamma-ray imaging devices which usually consist of two position and energy sensitive detectors working in time coincidence. Ideally, the gamma-ray undergoes a Compton interaction in the closest detector layer which is referred to as scatterer and deposits the rest of the energy in the second detector which is called the absorber. Using the kinematics of Compton scattering, the origin of the gamma-ray can be constrained to a cone surface. As a result of the intersection of different cones, information of the activity distribution can be obtained. CCs have been originally designed for astronomy applications. Their application in medical imaging was first proposed in [1]. Thenceforth there has been a growing interest in their application in the field of medical imaging and therapy monitoring. Since Monte Carlo (MC) simulations play an essential role in the design and optimization of a system, we present in this work an extension of GATE [2] with the aim of supporting CC simulations. GATE is an open-source simulation toolkit based on Geant4, dedicated to medical physics applications, that already contains modules for SPECT and PET imaging simulations.