Police went to the car park on Missenden Road and Lucas Street following reports of the escape,and officers from the Inner West Police Area Command Police called in experts from Taronga Zoo to help round up the rogue primates.
"They are currently contained and police are working with experts to safely return them to their facility,"a police spokeswoman said.
A spokesman from Sydney Local Health District confirmed three baboons had been found loose on the hospital's campus earlier on Tuesday and there was no threat to the safety of staff,patients or visitors of the hospital.