Hybrids of the following duck species, collected in the Netherlands, are listed and described: Anas platyrhynchos L. X Anas acuta L. Anas platyrhynchos L. X Anas penelope L. Netta rufina (Pallas) X Anas platyrhynchos L. Netta rufina (Pallas) X Aythya ferina (L.) In each case the hybrid proved to be intermediate between the presumed parents. An aberrant hybrid of A. platyrhynchos and A. acuta probably arose from a mating of acuta with a colour-aberration of platyrhynchos.