The objective of the present study is to evaluate the RibEye system used to obtain deflections in impactrelated tests. A description of the system is presented based on the specifications of the manufacturer. Evaluations included chest compression tests under varying loading condition:​ mid-sternum, offset, and diagonal loading. Accuracy assessment tests included:​ sternum-mounted, and rib-mounted LEDs with and without initial chest rotation about the zaxis, and indenter-mounted LEDs. These quasi-static tests were followed by pure and oblique pendulum tests to the thorax at velocities of 4.8 and 6.6 m/s. LEDs on the sternum responded similar to the available internal chest potentiometer. The accuracy of the system depended on positioning of the LEDs on the rib, magnitude of rib deformation, and potential interference from devices such as the presence of the internal chest potentiometer. Signal drop out depended on the type of indenter, with diagonal loading producing more signal loss. The deflection response along the x-and y-directions were deemed to be reasonable in oblique loading tests. Results from dynamic tests indicated that light interference from the internal component(s) restricts the ability of the system to obtain accurate deflections including signal drop out. In oblique tests, the system captured the asymmetric motions of the chest by demonstrating greater deflections on all left side ribs than right side ribs, thus showing its potential under this loading condition. The current fundamental evaluations helps in understanding of the performance of the system as installed in the midsize male Hybrid III dummy.