The Old World camels of the genus Camelus have diverged from the New World camels of the genera Lama and Vicugna over a period of more than a million years of their evolution. The two groups of modern camelids have evolved numerous different adaptations, but they retain a number of phenotypic similarities. Chromosome preparations made in this laboratory from cultured cells of various tissues demonstrate notable similarity of the karyotypes of two Old World camelids and one of the New World forms. Comparison with the work done by Benirschke’s group indicates that current methods of preparation present a remarkable uniformity of the karyotypes among all of the camelids. One female guanaco possessed a negatively heteropycnotic X in all cells examine