Acoustic Emission (AE) monitoring is an effective tool for prioritising more conventional non-destructive inspections of above ground tanks, either process or storage vessels. Results obtained from AE monitoring may be assessed against an existing data bank permitting plant management to prioritise maintenance to tanks with high active corrosion rates or leaks. AE results may be used to extend inspection periods of tanks without leaks or active corrosion. This paper covers the theory of AE leak detection and corrosion monitoring including some background research into the difference between AE from corrosion and leaks. It looks at the equipment used and provides a summary of tank test results conducted by ATTAR and other overseas organisations as well as reviewing AE tank inspection economics.