In contrast to findings in many other species, the centromeric heterochromatin in cattle, goats, and sheep is unstained when the C-band method of Arrighi and Hsu (1971) is used. However, a modified C-band technique stains the centromeric heterochromatin strongly. This material also stains strongly with an acridine-orange reverse-banding method. The G-band patterns of some of the chromosomes of these three species show striking similarities, suggesting identity. Even some parts of the metacentric chromosomes of sheep, presumably resulting from Robertsonian fusions, can be identified as nearly unchanged chromosomes of the goat or of cattle. Auto-radiographic studies reveal that these centromeric regions replicate their DNA late in the S phase. Both 3H-thymidine and 3H-deoxycytidine are incorporated at these centromeric regions.