A Sydney man has found a horse's head on the bonnet of his car, which was also badly damaged, outside his house in Sydney's north-west.

Police said the man was awoken by loud banging outside the house in Naomi Street, Winston Hills, about 2.30am on Thursday.

When he went outside, he made the grisly discovery, which is reminiscent of a scene from the 1970s film The Godfather.

Police said a large trail of blood led from the driveway.

In one of the best-known scenes from The Godfather, Mafia boss Don Corleone arranges for a horse's head to be put into the bed of movie producer Jack Woltz to intimidate him into giving his godson a part in a production.

Police said the Winston Hills head appears to have been obtained from a local abattoir.

The council disposed of the head and police are examining the damaged car.

Police said anyone who saw or heard anything suspicious near Naomi Street this morning should contact Parramatta police or to call Crime Stoppers on 1800 333 000.