A man from Seven Hills saw a brown wooden box on the road at the intersection of Caroline Chisholm Drive and Langdon Road at Winston Hills in Sydney's west about 1pm on Saturday.

He handed the box to police from the Quakers Hill Local Area Command.

Inside the box were original World War I medals in good condition, police said.

"While the recipient of these medals may have passed away, we believe there are family members out there who would really appreciate having them returned home," Duty Officer Chief Inspector Garry Sims said.

"They would be of high sentimental value to the family of the soldier who fought and served his country valiantly to earn these medals."

Among the collection is the 1914-15 Star, which was awarded to those who served against the Central European Powers in any theatre of the Great War, including the Gallipoli campaign.

Also in the collection is a British War Medal, awarded to officers and men of British and Imperial forces who served during World War I, as well as the Victory Medal, awarded to those who entered a theatre of war during the Great War.

The box also contains a Silver War Badge, given to service personnel who were honourably discharged due to wounds or sickness.

There is also a Returned Sailor's & Soldier's Imperial League of Australia Badge.

Police will liaise with the NSW RSL sub-branch in an attempt to locate the owners.

Anyone with information about the medals is urged to contact Riverstone police station or Crime Stoppers on 1800 333 000.