Interproximal grooving of the teeth is a form of nonmasticatory wear commonly found in precontemporary human populations. While its cause is debated, it is thought to be due to the repeated abrasion of fibrous materials across the distal surfaces of teeth during processing. This report describes the presence of interproximal grooves on the distal surfaces of the lower second molars of the WLH 4 individual from the Willandra Lakes in New South Wales, Australia. Although there has been considerable discussion regarding the distinct occlusal wear pattern in WLH 3, this is the first recorded instance of an interproximal wear pattern in the Willandra Lakes region, and has implications for our understanding of cultural behaviors practiced by those populations in the late Holocene.