The radiation-hydrodynamic ICF3D code We describe a three-dimensional high-temperature plasma simulation computer code ICF3D developed at the Lawrence Livermore National Laboratory. The code is portable; it runs on a variety of platforms: uniprocessors, SMPS, and MPPs. It parallelizes by decomposing physical space into disjoint subdomains, and relies on message passing libraries such as MPI. ICF3D is written in the object oriented programming language C++. The mesh is unstructured and consists of a collection of hexahedra, prisms, pyramids, and/or tetrahedra. The hydrodynamics is modeled by discontinuous finite element method which allows a natural representation of inherently discontinuous phenomena such as shocks. Continuous processes such as diffusion are modeled by conventional finite element methods. ICF3D is modular and consists of separate equation-of-state, hydrodynamic, heat conduction, and multi-group radiation transport (diffusion approximation) packages. We present results on problems relevant to inertial confinement fusion (ICF) which are obtained on a variety of computers, uniprocessors and MPPs.