An award-winning four-foot long rabbit is thought to have been stolen from its enclosure.
Darius, a continental giant rabbit, went missing from his home in Stoulton, Worcestershire, on Saturday night.
His owner Annette Edwards has offered a £1,000 reward for his return and said it was a "very sad day".
At 129cm (4ft 2in) long, Darius is a record holder after being named the world's longest rabbit in 2010.
West Mercia Police said it is believed Darius was stolen from his enclosure, which is in his owners' garden, overnight on Saturday.
Ms Edwards said Darius is "too old to breed now" and pleaded for his safe return.
He was named as the longest living rabbit by Guinness World Records in April 2010, when he was measured for an article in the Daily Mail.
Ms Edwards said he claimed the title from his mother Alice, and he was her fourth award-winning rabbit.