[6] A majority of Miller's langur's diet comes from young leaves and leaf shoots, and their next most important food item is unripe fruit.

[4] Miller's langur is listed as endangered by the IUCN due primarily to habitat loss, fragmentation and hunting.

[9] Limited to a geographical range from the central coast of East Kalimantan to the Kutai National Park, the species is highly regarded as an endemic and extremely vulnerable primate.

Experts speculate it becoming extinct in the very near future, due to multiple factors such as deforestation and overhunting for its bezoar stones and as a food source.

[10] The bezoar stones, which are smooth, hard mineral deposits found in the digestive tracts of some animals, are used as good luck charms, and also for its alleged ability to neutralize some poisons, but only occur in a minority of the monkeys.

[4] In October of 2019, Forrest Galante led an expedition and recorded the first video evidence of a Miller's langur in the 21st century.