The anterior inferior tibiofibular ligament was evaluated in 46 preserved specimens with a mean age of 73.8 years. A classification system was devised to encompass the observed variations in ligamentous structure. Particular emphasis was placed on evaluating the extent of impingement between the inferior border of the ligament and the talus. It was determined that the presence of a separate inferior fascicle is not a prerequisite for impingement. However, a triangular, beveled region located anteriorly on the border between the trochlear and lateral surfaces of the talus was identified in association with anterior inferior tibiofibular ligament impingement.