Additional, or supernumerary, teeth occur in most mammalian taxa, although they are better recorded in some species than in others. As part of a larger biometric study, incidence of visible supernumerary teeth was recorded in the skulls of 1228 pinnipeds (seals, sea lions, and fur seals). Results showed that supernumerary teeth only occurred in the postcanine (molars and premolars) tooth row. It was also found that 3.3% of otariids (sea lions and fur seals) and 4.7% of phocids (‘true’ seals) possessed supernumerary postcanines. Out of a total of 52 supernumererary teeth recorded, only six were morphologically abberant; all the others played a functional role in the normal tooth row.