A koala breeding program in Canberra has been given a boost with the arrival of a new female at the National Zoo and Aquarium.

Matilda is the third koala to join the zoo, which currently houses another female and male koala.

Keepers are hoping Matilda will take a liking to male koala Winston, during the breeding season from September until February.

Koala keeper Bec Scott says breeding in captivity is relatively successful.

"We're quite hopeful that we will have some little joeys running around in the not too distant future," she said.

"We have tried breeding in the past with Eucky [the existing female koala] and Winston, which is yet to be successful.

"We're looking forward to see what happens with Matilda and Winston."

Koala populations in Queensland, New South Wales and the ACT were placed on the endangered animals list earlier in 2012.

In the ACT, no koalas in the wild have been reported since the 2003 bushfires.

Ms Scott says it is vital the zoo plays its part in ensuring the future of the animal.

"The fact that they've been classes as vulnerable now in those states and territories is very exciting for them," she said.

"It does mean that we're now recognising that something does need to be done.

"Their future at this stage is still uncertain."