Time reversal active sensing using Lamb waves is investigated for health monitoring of a composite structure. In the present work experiments were conducted on a glass/epoxy composite plates to study the time reversal behavior of A0 and S0 Lamb wave modes. PZT wafer sensors were surface bonded to the structure for generation and reception of the Lamb wave modes. Time reversal experiments were further carried out on carbon/epoxy composite t-pull specimen. The specimen was subjected to a tensile loading in a Universal testing machine. The PZT sensor measurements were carried out for healthy and also during different stages of delamination due to tensile loading. Time reversal of A0 and S0 mode was applied for both healthy and delaminated composite structures. In this work, the shape of the time reversed Lamb wave in the presence of delamination was studied experimentally. This study aims in showing the effectiveness of Lamb wave time reversal for damage detection in health monitoring applications. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc.