A man who answered the doorbell at his home in Sydney's west found a baby girl wrapped in a blanket abandoned on his doorstep, police say.
Police are now searching for the parents or guardian of the child, who police estimate is about one year old and appears to be in good health.
The girl, who is of Asian appearance, was wrapped in a light green blanket with a picture of an owl embroidered on the front. A bag containing a bottle and formula had also been placed beside her, police said.
The man told police he was at his home on Kirkham Road in Auburn with his family about 9.50pm on Monday when the front doorbell rang.
As the man answered the door he heard a car speeding away and found the abandoned child.
The man or his family had never seen the child before and did not know why she had been left on their doorstep. They immediately phoned police and cared for the baby until officers arrived.
A NSW Police spokeswoman said the man and his family were quite taken aback by the discovery, but they were a "lovely family" and had taken the child in immediately.
Police believe whoever abandoned the child must have been "under considerable stress", the spokeswoman said.
The baby was dressed in a black and white long sleeve top with a white sleeveless jumper over the top, and a pair of grey shorts with grey and black striped socks.
The car seen leaving the area at the time has only been described as a late model white sedan.
Police have urged anyone with information that may help to identify the child and locate the child's parents or guardian to call Flemington Police on (02) 9646 8699, or Crime Stoppers on 1800 333 000. Callers can remain anonymous.