The biomechanics of ankle injury have been studied extensively, primarily through mechanical testing of human cadavers. Cadaveric testing is an invaluable methodology in biomechanics, because the magnitude and direction of the loading can be measured precisely and correlated with the resulting injury pattern. Clinical and epidemiological studies provide useful descriptions of injury patterns that occur in the real world, but their retrospective nature precludes a definitive analysis of the forces that caused the injury. Understanding the mechanism of ankle injuries is essential for developing countermeasures to prevent injury and for reconstructing injurious events. Knowledge of an injury's mechanism can also suggest potential associated injuries, which is helpful in diagnosis and treatment. The purpose of this review is to summarize the published research on ankle injury mechanisms with an emphasis on biomechanical experiments on human cadavers. Injury patterns are described based on the principal axis of force or torque producing the injury in conjunction with off-axis forces and out-of-plane foot positions. A mechanistic description of ankle injuries is complicated by the fact that the same mechanism can sometimes produce different injuries and the same injury can sometimes be caused by multiple mechanisms. Nonetheless, a framework for relating injury mechanisms and injury patterns is a valuable tool in the understanding, prevention, and treatment of ankle injuries. Clin. Anat. 24:350–261, 2011. © 2011 Wiley-Liss, Inc.