Zoo keepers in Kent are having to learn French in order to speak to the baboons at Port Lympne wild animal park.
The problem appeared when the apes arrived from a zoo in France, reports the Guardian newspaper.
Staff found the animals didn't respond to English, but when they used French words, like dejeuner for lunch, the baboons came running.
Veronica Chrisp, a zoo spokeswoman, said: "I expect we'll have to carry on speaking French to them forever."
The 19 Guinea baboons came from Paris zoo, which had too many of the creatures.
But Ms Chrisp is worried in case the next load of baboons may come from somewhere with a more difficult language - she may have to hire interpreters!