The metacarpophalangeal joint (MCP joint) is a diarthrodial joint that permits flexion and extension, abduction and adduction, and rotation (pronation and supination) of the proximal phalangeal base (PPB) on the metacarpal head (MCH). Determination of the distribution and magnitude of joint contact area is necessary to understanding the effects of loading on articular cartilage. For example, accurate assessment of MCP joint contact area is needed for various methods used to quantify joint stress such as mathematical modeling and finite element analysis. Traditionally, such data have been obtained from cadaver specimens. Recently, Magnetic Resonance Imaging (MRI) was shown to be a valid method of quantifying the joint contact area indicating the potential for in vivo assessment. In this study, MRI was used to quantify in vivo MCP joint contact area, contact distribution and joint motion. Eight males participated in this study. Cartilage-enhanced MR images were obtained at -30, 0, 45, 60 degrees finger flexion. This study highlights the differences in MCP joint contact area and joint motion between different finger flexion postures and geometries of joint surfaces.