Mechanisms are one of the fundamental elements used by engineers in the design of machines. The design or synthesis of these elements has been studied for hundreds of years. More recently, the focus of kinematic synthesis research has been in reformatting the graphical synthesis methods into an analytical form compatible with computer processing. One of the thrusts of this research concentrates on the human/computer interface (HCI) between the user and the computer design software. The work presented in this paper addresses this issue of developing a new HCI for mechanism design based on virtual reality techniques. Current computer-aided mechanism design can be seen in the areas of analysis, topological, and dimensional synthesis (Erdman 1995). In each of these areas, the trend is toward developing user interfaces that are more compatible with the cognitive and perceptual nature of the designer. Mechanism synthesis computer programs like KINSYN (Rubel et al . 1977), LINCAGES-4 (Erdman and Riley 1981) and SPHINX (Larochelle et al . 1993) utilize the traditional HCI of monitor, keyboard and mouse. More recently, virtual reality (VR) is being examined as a natural human interface for mechanism design. Osborn (1994) developed the first virtual environment for the synthesis of spherical four-bar mechanisms, SphereVR, which used the Newton-Raphson iterative approach to solve the design equations. This paper takes a slightly different approach by combining the reliable and robust solution algorithms of SPHINX1.0 with VR technology. VR is used for all interaction, manipulation, and navigation throughout the design process, while SPHINX1.0 computational routines are used for computing the solution mechanisms. Natural and intuitive skills of the designer are used through reliance on a head tracked three-dimensional display and three-dimensional interaction. The result is a program called VEMECS (Virtual Environment MEChanism Synthesis). This paper outlines the organization and operation of VEMECS, and concludes with a discussion of the lessons learned in development and implementation of this approach.