Thick filament-wound composite materials are particularly attractive for use in solid rocket motor structures. However, these materials are difficult to inspect because of the scattering losses associated with multiple fiber layers. Damage caused by either low or high velocity impact which results in matrix cracking, delaminations and broken fibers cannot be tolerated because of the possibility of catastrophic system failure. American Research Corporation of Virginia has performed a 2-year Phase II Small Business Innovation Research contract to develop an ultrasonic inspection system for graphite/epoxy rocket motor canisters [1]. This paper details the experimental apparatus and testing of rocket motor canisters, presents testing results and discusses observations and detection thresholds.