This paper presents a measurement program of a sitting 50th percentile Hybrid III Dummy to determine a database for computer simulations. Geometrical, inertial, joint property and surface compliance measurements have been carried out. A description of the measuring methodology is given.On the basis of these measurements a 20 segment database for the MADYMO 3D occupant simulation program is developed. The major advancements of this database compared to an earlier 15-segment database developed by TNO * can de summarized as follows: Five additional segments are incorporated in this database to account for the hands, the shoulders(clavicles) and the sternum. The database includes a complete omni-directional description for the neck as well as the lumbar spine. A detailed mathematical surface description is available, for instance to be used for computer animations. Segment ellipsoids for contact interactions have been determined in a more accurate way. Joint properties are determined with a special developed static joint measuring device. Segment surface and thoracic stiffness data are based on a large series of tests with different impactor faces, including tests with a seat belt.