This paper describes the development, testing and application of a continuous acoustic monitoring system to detect and locate corrosion-induced failures of tensioned steel elements in buildings, bridges and pipelines. The monitoring system utilizes acoustic sensors distributed about a structure. Data is processed on-site and transmitted over the Internet to a central processing facility where proprietary processing software is used to generate reports summarizing the time, location and classification of recorded events. Case studies describing the various applications and testing of the system are presented and discussed.