Composite materials in comparison with metals have many advantages such as high strength and corrosion resistance, therefore are strongly used in fields of civil and military applications. However, defects such as delamination, fiber cracking, fiber and matrix separation and the like are more critical than steel structures. As a result, the use of accurate and cost-effective method for monitoring of composite structures is very important. In this regard, using ultrasonic guided wave is growing rapidly in many industries which is because of guided wave's characteristics such as their high sensitivity to defects, ability to propagate in large range as well as some other practical points. In this paper, after introducing ultrasonic guided waves, accessing the features of the signal produced due to the delamination in a fiberglass plate is discussed. Subsequently, utilization of piezoelectric probe of guided wave and its measurement will be elaborated. Last stage of this study will discusses analysis of signals received under assortment of conditions in the measurement process, upon which, a systematic approach in delamination detection will be introduced.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.