Due to their specific characteristics, the usage of composite materials is extended everyday. In order to prevent the catastrophic failure of composite structures, several non destructive test methods have been developed. In this study, a new technique to evaluate these structures by using liquid-crystal thermography is presented. Temperature gradients produced by sensitive liquid-crystals are used to detect invisible defects of composite structures. The effect of constituent materials and defect location is investigated and advantages/disadvantages of the new method are discussed. Based on the results from this study it can be concluded that the liquidcrystal thermography can be used as an inexpensive method in inspection of composite structures. Keywords: Non
