Ankle-foot orthosis (AFO) are commonly used in clinical practice to supplement gait disabilities of hemiplegic patients secondary to cerebrovascular accidents and brain injuries. Pathological motion of the ankle-foot complex namely foot drop is one of the major problem in these patients whereby it is a problem involving excessive and uncontrolled plantar flexion. The objective of this study is to develop a 3-dimensional (3-D) finite element model of the foot and AFO, using actual geometry of the foot skeleton and soft tissues which were obtained from 3-D reconstruction of CT scan images in contact with the polypropylene AFO by simulating the foot drop problem. This study will focus on the stress distribution in the AFO under normal and pathological conditions.