A high speed 16 mm cineradiographic system originally developed at the University of Michigan Transportation Research Institute (UMTRI) for use in biomechanics research has been undergoing continuous upgrading in capability. In addition to changes in the structural aspect of the cineradiography, improvements have been made in the procedures used to obtain better image quality, as well as in the methods for interpretation of the digitized results. The current improvements in the system include (1) filtering of the x-ray source before penetration of the subject to increase image contrast and to protect the image tube; (2) hypersensitization of the film to increase its effective speed; (3) development of a neutral density radio-contrast medium for outlining anatomic structure without using the vascular system; and (4) development of procedures for obtaining analytic information about motion of nonrigid anatomic structures from digitized film. This system now consists of cameras that view a 50 mm (2 in.) diameter output of a P-11 phosphor of a high gain, four-stage magnetically focused image intensifier tube, gated on and off synchronously with the motion picture camera shutter. A lens optically couples the input photocathode of the image tube to an x-ray fluorescent (rare earth) screen image produced by a smoothed dc x-ray generator of a conventional type. The system is capable of looking at a large variety of anatomic structures under a wide range of dynamic loading conditions.