Most of the research on Structural Health Monitoring employs guided waves only to detect and locate damage in a plate-like structure. The purpose of this paper is to present a Diffraction Tomography based imaging method, using experimentally-determined scattered fields (Lamb wave signals) and numerically computed GreenÕs function, to characterise laminar damage in an aluminium panel. The approach is based on a recently derived extension of Diffraction Tomography which utilises the multi-static scattering matrix constructed from the measurements of the scattered field for every source and receiver pair, as well as the GreenÕs function of the structure which is its response to a point source. The imaging results have provided for the first time an accurate characterisation of damage geometry and size derived from experimental data. These results are shown to compare favourably with those obtained from computational data, and they are significantly more accurate than previously reported results.