Thesis describes the identification of structural damage of reinforced concrete structures using nondestructive ultrasonic technique. Many important methods for nondestructive assessment of concrete and reinforced concrete structures are described. The use of new state-of-the-art nondestructive ultrasonic device Pundit PL-200PE of Swiss manufacturer Proceq for evaluation of concrete structures is presented, which is based on ultrasonic Pulse-Echo technology. The device was tested on different existing structures, ranging from old, weakly reinforced structures with high percentage of voids, to different types of new, highly reinforced concrete structures. Some new, state-of-the-art functionalities of the device are presented. It was found, that the device is more appropriate for use on newer structures, made of relatively sound concrete, rather than on old, highly porous concrete structures. However, the device is capable of high-speed evaluation of concrete thickness and identification of cracks and honeycombing over large concrete surfaces.