Three species of whale-lice are recorded from Dutch waters: Platycyamus thompsoni (Gosse, 1855), Cyamus catodontis Margolis, 1954, and Isocyamus delphinii (Guérin-Méneville, 1836). Cyamus catodontis is recorded moreover for the first time from several subantarctic localities. Isocyamus delphinii is recorded from a new host, Phocoena phocoena (Linnaeus, 1758). The records for C. catodontis and I. delphinii constitute considerable extensions of the known range.