Acorn barnacles with boreholes were recovered from a Pleistocene marine deposit on Navarino Island, on the southern coast of the Beagle Channel. Balanomorph shells were identified as Balanus laevis (Bruguière, 1789), and a few bear small round holes located generally on the middle or apical part of the parietal plates, thus suggesting that they represent the work of small muricid predators. If so, this study is the first record of drilling predation on fossil barnacles reported in southern South America.