This study presents a three-dimensional computer-modelling system based on Transom JACK software, with 3D objects/equipment and human subjects with specific anthropometric measurements to visualize and evaluate human-machine interaction. A computer simulation method is then adopted to evaluate some VDT (Visual Display Terminal) workstations to determine whether they are appropriate for use by wheelchair users. The study indicates that currently available commercial computer desks present difficulties, in terms of both spatial design and reachability of peripheral devices, to wheelchair users. Some VDT tasks result in awkward body postures in virtual subjects. New VDT workstations are designed and recommended to solve the shortcomings found.