They have a dark red coat, which can range in color from orange red to black. Their coats are shaggy and thin. They have high foreheads, which lack the pronounced brow ridge seen in other primate species. A fringe of hair can be seen lying towards the forehead. Their faces are almost hairless and they have a massive bulging muzzle.
Adults have whiskers on the chin and cheeks.
They develop cheek pads at maturity, and they may become very pronounced in males. They have small hairless ears. Adult males have pronounced fatty flanges around their eyes and a throat pounce containing large laryngeal air sacs. The presence of this throat pouch allows the males to communicate over great distances. Their voices can be heard over a half a mile away.