Acoustic emission (AE) is applied to a variety of fields related to concrete engineering. With increasing need for maintenance, the non-destructive evaluation of in-service structures is being actively investigated all over the world. In particular, there is a realization that a number of civil structures are approaching the limit of their service life in Japan. AE techniques look promising as a means of inspecting such structures and evaluating their structural integrity. In addition to the demand for maintenance, the application of AE to construction monitoring is receiving.fresh attention. Research activities related to concrete technology are summarized with a brief review of historical developments.