Burglars stole a safe from a village pub during the early hours of Thursday morning last week.
Offenders gained entry to The Greyhound in Chesham Road, Wigginton, via the back door; once inside they removed the safe before making off.
Police were called to the scene at 12.51am, but the break-in happened after the pub had closed for the night.
Anyone with information that could assist the investigation is asked to contact Hertfordshire Constabulary via the non-emergency number 101, quoting crime reference D3/16/731.
Alternatively you can call Crimestoppers, anonymously, on 0800 555 111 or via their website at www.crimestoppers-uk.org