The gorillas face loss of habitat from deforestation, as trees are chopped down from fuel, as well as from poaching.
Twenty-nine percent of all monkeys, apes and gorilla species are now in danger of going extinct, according to the report by the Swiss-based World Conservation Union (IUCN).
It highlighted 25 species it said were most endangered, including the Greater bamboo and white-collared lemurs in Madagascar, and the exotically-named Miss Waldron's red colobus monkey in West Africa.
"You could fit all the surviving members of these 25 species in a single football stadium; that's how few of them remain on Earth today," warned Russell Mittermeier, chairman of the IUCN's Primate Specialist Group.
The report, compiled by 60 experts from 21 countries, warned that failure to respond to these threats could lead to the first primate extinctions in over a century.
"Hunters kill primates for food and to sell the meat; traders capture them for live sale; and loggers, farmers, and land dev