To asses phylogenetic relationships among the higher ruminants (infraorder Percora, order Artiodactyla), we analyzed K-casein DNA sequences, including 434 nucleotides of the fourth exon. The higher ruminant families Bovidae, Cervidae, Giraffidae, and Antilocapridae each have monophyletic K-casein sequences. Maximum parsimony and distance analyses identify Giraffidae as a sister group to either Cervidae or a Bovidae-Ceridae clade and Antilocapridae as a sister group to a Bovidae-Cervidae-Giraffidae clade. At a higher level these four families occur as a monophyletic clade relative to