Tom Kitten and Jemima Puddle-Duck were among a number of items of china and pottery stolen in a raid on an Arundel house.
The burglary happened in Torton Hill Road at some time between 1.30pm and 11.30pm on Wednesday, February 13.
Other pieces stolen included Royal Doulton pottery, one named The Green Lady, Bow China figurines and other Beatrice Potter characters.
Also taken were several water colour paintings and jewellery, most notably a gold necklace with a small, ornate butterfly charm.
Detective Constable Della Squires said: "These are items of great sentimental value.
"If you have been offered them or have any other information about the burglary, please call Sussex Police on 101 quoting serial 1649 of 13/02.
"Alternatively, contact the independent charity Crimestoppers anonymously on 0800 555 111."