An automated motion measurement system using a television camera interfaced to a computer was constructed and evaluated to determine its applicability to clinical gait analysis. Experimental data indicate that the motion measurement system has a resolution of 1 part in 2000 and a static accuracy of 1 part in 1000 with a worst case dynamic error of 1 part in 300. The study has also shown that this system can reliably track multiple passive markers on a human illuminated with infrared light emitting diodes. This approach minimizes patient distraction, since the illumination is not visible, and reduces patient discomfort since a marker telemetry back pack system, to control active markers, is not needed. Further, the motion measurement system has been successfully demonstrated under conditions similar to those expected in a clinical environment.