The fiber optic sensors which can readily be integrated with smart materials and structures offer an immense potential in the realization of intelligent systems. This paper presents an overview of fiber optic sensors and their application to smart structures. The advantages of fiber optic sensors are freedom from EMI, wide bandwidth, compactness, geometric versatility and economy. In general, FOS is characterized by high sensitivity when compared to other types of sensors. Fiber optic sensor technologies are finding growing application in the area of monitoring of civil structures. In large part due to exceptional advances in fiber telecommunications technologies, the costs for fiber sensors has been dropping steadily, and this trend will continue. Furthermore, measurement capabilities and system configurations that are not feasible with conventional technologies are now possible with fiber sensors, enabling previously unobtainable information on structures to be acquired.