A karyotype of the gibbon, Hylobates, has been prepared based on the chromosome banding patterns produced by quinacrine, trypsin-Giemsa, and centromeric heterochromatin stains. The banding patterns of H. lar and H. moloch are virtually identical. No brilliant quinacrine-fluorescent areas are present. The banding pattern of most of the gibbon chromosomes show less resemblance to those of the human, chimpanzee, gorilla, or orangutan than the chromosomes of the higher primates do to each other, suggesting a relatively large evolutionary separation of the gibbon from the higher primates. A pericentric inversion of chromosome 7 is present in one gibbon.