The application of high frequency dielectric measurements to the examination of adhesively bonded structures is described. The use of the frequency dependence of the real and imaginary parts of the complex permittivity for the identification of water ingress into a bonded structure is discussed. Pulse measurements allow identification of the spacial distribution of impedance changes in the bond and allow identification of voids and also non bonded areas in new as well as aged bonds. The paper considers the scope of the method for the NDT examination of new and aged adhesively bonded structures.