Detailed investigation on biomechanics of a complex structure such as the human lumbar spine requires the use of advanced computer techniques for both the geometric reconstruction and the stress analysis. In this study, an automated scheme is developed to generate the required three-dimensional finite element grid of a human ligamentous lumbar spine. The computer-based medical images (CT-scans) of a cadaveric lumbar spine are used to automatically reconstruct the geometry and the grid of the tissues. The data are then transferred to a mainframe computer in a format suitable for an existing nonlinear finite element code. The process has been designed to allow for a number of user-defined parameters such as the number of elements representing the intervertebral discs and the degree of smoothing of the facet articulating surfaces. This finite element mesh can be used for a detailed stress analysis of the human lumbar spine to understand its mechanical function in both normal and perturbed states. The developed interactive system is also helpful from a diagnostic point of view.