This article discusses the advantages of off-line programming techniques, particularly relating to the use of 3D graphical simulation as a method of planning robot cells and proving and generating robot programs. A unique installation in the UK, consisting of a computer-integrated off-line programming system at the Welding Institute, Cambridge, is briefly described as an illustration. This robotic cell contains a Prime Medusa CAD system for component design, linked to the GRASP 3D graphical system for robotic simulation. The robot programs produced by GRASP are post-processed and transferred to a KUKA industrial robot using a RCM3 controller.