The following nine species of primates are found in and around Bukit Lawang, comprising two great apes, two lesser apes, four old-world monkeys, and one species of lorisid.

• Homo sapiens - for many visitors why they return to Bukit Lawang
• Pongo abelii - Sumatran orangutan - why most people come in the first place, you can read about orangutans here.
• Symphalangus syndactylus - siamang (may be referred to as black gibbon, but this describes many gibbons), you can read about gibbons here.
• Hylobates lar vestitus - lar gibbon (white-handed gibbon)
• Macaca fascicularis - long-tailed macaque - you can read about macaques here.
• Macaca nemestrina - Southern pig-tailed macaque
• Presbytis thomasi - Thomas' langur (Thomas' leaf monkey) - you can read about leaf monkeys here
• Trachypithecus cristatus - Silvery lutung (silver leaf monkey)
• Nycticebus coucang - Sunda slow loris