FluDAG: A CAD based tool for high energy physics. As part of the expansion of the Direct Accelerated Geometry Monte Carlo (DAGMC) toolkit to support other Monte Carlo codes, FluDAG (FLUKA integrated with DAGMC) was developed. There has been increasing demand from the high energy physics community regarding Computer Aided Design (CAD) geometry support in Monte Carlo codes. In this paper, the development and validation of FluDAG is discussed and its application to a number of high energy physics experiments is demonstrated, along with its validity relative to native FLUKA calculations.