Acoustic emission (AE) was used to monitor the failure process of hardwood and softwood test-pieces under static and fatigue torsional loading. In static torsional-loading tests, acoustic activity indicated some microcrack initiation before the visible cracking in both hardwood and softwood test-pieces. Hardwood produced more AE counts than softwood during testing, and the grain angle of test-pieces influenced the total AE counts. During torsional fatigue fracture, increased acoustic activity indicated the onset of microcrack formation. Fatigued test-pieces produced more total AE counts during fracture than static test-pieces, provided the angle of twist exceeded a minimum value. The results show that it is possible to monitor and analyze the failure process in wood when under torsional loading using acoustic emission techniques. (c) 2006 Springer Science+ Business Media, Inc.