One of the most important parameters in the area of structural inspections is nondestructive testing. In recent years, a new approach known as "ultrasound guided waves" has been developed in the field of ultrasonic testing. The main advantages of this method are ability of propagation along the structure and inspection of long distances, high speed and low cost. In this study, a sinusoidal input signal with three pulses has been used for excitation of guided waves. These waves have been propagated along the pipe and data capturing has been performed in three positions. Afterwards, a saw cut has been applied on the pipe as a crack and the receiving signals have been recorded in the same positions. Upon capturing, signals have been processed and compared via wavelet analysis. Variations in wave amplitudes due to passing the crack has been investigated and signals have been compared simultaneously in both time and frequency domain by means of wavelet analysis. Results indicate that even if the crack is not detected, presence of crack in the way of passing wave will affect the amplitude of propagating wave, yet it does not have any effect on the frequency and time contents of the signal.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.