Lancashire Police said the burglary took place in broad daylight and a total of five medals were taken.
The force has shared pictures of each of the medals and is appealing for the public's help in finding them.
A police spokesman said: "We are appealing for information after a burglary in Penwortham on Sunday, June 13.
"Offender(s) have entered the victim's property during daylight hours and stolen a tin containing five military service medals belonging to the victim that were awarded to him for his service in Afghanistan and Iraq.
"If anyone has any information in relation to this burglary or the known whereabouts of these medals, please email [email protected]"
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