Nearly half the world's monkeys and apes are in danger of becoming extinct, wildlife experts are warning.
A big survey by the International Union for Conservation of Nature (ICUN) found hundreds of species are under threat.
Lots of them are in danger of dying out because the tropical forests where they live are being destroyed, while others are being hunted for food.
Out of 634 known species, 70 have been listed as critically endangered, 140 as endangered and 95 as vulnerable.
Jean-Christophe Vie, from the IUCN species programme, said the results of the survey were probably the worst assessment for any group of species on record.
"It is quite spectacular; we are just wiping out primates," he said.
"The problem with these species is that they have long lives, so it takes time to reverse the decline. It is quite depressing."
Conservationists are worried the Bouvier's red colobus and Miss Waldron red colobus monkeys may already be extinct as neither have been seen for more than 25 years.
But it's not all bad news. Programmes to boost Brazil's populations of golden lion tamarins and black lion tamarins ARE working.