This work presents an innovative Structural Integrity Monitoring concept based on embedded optical fiber distributed Rayleigh back-scattering strain sensing. The UAV wing main spar strain distribution, under load, was recorded periodically during service. These strain measurements were analyzed and compared to a baseline record in order to identify changes in the strain distribution profiles as an indication for stiffness change that may result by damages or material deterioration. I. Introduction The high strength-to-weight ratio, corrosion resistance and fatigue durability of composite materials make them an excellent candidate for use in UAV structures [1]. However, the choice of composite materials for primary UAV components, such as the wing, imposes great challenges on scheduled maintenance procedures since conventional inspection procedures are difficult to apply in the case of complex composite-based structural components. In addition, the available NDT methods require highly trained technicians, so that operating costs are higher [2]. In this work an innovative inspection procedure, based on the Rayleigh backscattering distributed strain sensing technology, of a High-Altitude Long Endurance (HALE) UAV wing is presented. In this procedure, an embedded optical fiber measures the strain distribution on the wing due to an external controlled loading. Measurements taken periodically during service are compared in order to monitor the structural integrity of the central wing over time. Such an innovative approach, currently performed on ground, is a step towards a real time, in-flight, airborne structural integrity monitoring system that can increase UAV availability by requiring maintenance actions only upon a need.