Chevron Australia Pty Ltd is constructing a major gas processing plant at Barrow Island, WA. There are also substantial marine environmental values along with the widely known terrestrial environmental values of Barrow Island. Chevron has adopted an extensive, proactive program to protect the Barrow Island marine environment from introduced marine pest species (IMP), including mechanisms to prevent their arrival, a monitoring program to detect any IMP that do arrive, and action plans to be used should a pest species be detected. A monitoring strategy based on the national IMP monitoring protocols has been developed for Barrow Island. Remote operated vehicle (ROV) transects are made at six monthly intervals, at a combination of sites within and outside operational areas. The ROV surveys are supplemented by beam trawl sampling of biota in sandy areas. Quarterly monitoring occurs at four sites along the east coast of Barrow Island, using shoreline visual searches, settlement plates and sediment cores for toxic dinoflagellates. A similar quarterly sampling program has been established at the major supply bases at Henderson, south of Perth, and Dampier. This is to provide early warning should an IMP be detected in either locality. The combination of prevention, monitoring and response is a cutting edge response designed to prevent the introduction of IMP to Barrow Island waters.