Numbers have dropped from more than 80,000 in 2018, to fewer than 58,000 now.
Australia has lost around 30 percent of its koalas over the last three years.
It's because of droughts, bushfires, and developers cutting down trees.
The Australian Koala Foundation is urging the country's government to do more to protect the creature's habitat.
The non-profit group says numbers have dropped from more than 80-thousand in 2018, to fewer than 58-thousand now.