The Laotian langur has a dark black fur covering most of the body. The face is black with white hair encircling it. It has small ruft of black hair on top of the head.[8] New borns have a golden fur, which changes color while the monkeys grow. Juveniles have similar appearance to the adults though the fur color might be paler and are usually smaller in size. It has four fingers on the limbs with a short thumb, which is an adaptation for their arboreal lifestyle. The Laotian langur has a multi chambered stomach, which helps in the digestion of the plant matter.[8]
Laotian Langurs are primarily herbivorous and the diet consists of leaves, fruits, seeds, and flowers. They share a sympatric relationship with the Assamese macaque in their range. They often feed on the same trees, though the langurs occupy higher positions compared to the macaques. The langurs occupy limestone caves in rocks and cliffs, which serves as a shelter from predation and weather. As they consume a vegetation heavy diet, they often spend long times resting, and socializing.[8]