Purpose: The purpose of the study was to develop a finite element model of the human mandible and to compare the functional deformation predicted by the model with that detected clinically. Materials and Methods: Three patterns of mandibular deformation (medial convergence, corporal rotation and dorso-ventral shear) were studied clinically in 12 subjects using custom-fabricated displacement transducers mounted on endosseous implants in the premolar region. The mandibular arches of 12 patients with dental implants were modeled using finite element techniques based on computerized tomographic (CT) scan images of the jaw. Results: The finite element model was found to closely replicate the patterns of observed mandibular deformation. Differences between the predicted and measured deformation values were expressed as a percentage of the measured value and ranged between 0.0% and 22.2%. Medial convergence ranged between 14.4 and 58.4 µm. Dorso-ventral shear and corporal rotation ranged between 0.4 and 2.7 degrees. Conclusions: Using the finite element model described in this study, which represents the living human mandible, and clinical testing, there was close agreement between the predicted and measured deformation values. This study provided a high level of confidence in the finite element model and its ability to provide better insight into understanding the complex phenomena of functional mandibular deformation. (More than 50 references.) Keywords: finite element analysis, jaw deformation, stress