In this paper, we present a new framework for the use of Virtual Reality (VR) in engineering design for configuration applications. Traditional VR systems support the visual exploration of a design solution but do not assist the user in exploring alternative solutions based on domain knowledge. Extending previous work in the area of Intelligent Virtual Environment, we propose an intelligent configuration system based on constraint logic programming (CLP), integrated in a real-time 3D graphic environment. This type of integration facilitates the expression of design knowledge in the VE and enables the user to interactively solve and/or refine a spatial configuration problem. In the system described in this paper, the user can visually explore configurations, but his interaction with objects of the configuration problem triggers new cycles of constraint propagation from the modified configuration to produce a new compatible solution.