Police are investigating the theft of distinctive Shetland sheep from a field in Brattleby, north of Lincoln.
Six sheep were taken from the field close to Scampton. One is black with a white patch on its head, the others are a mottled colour beige and cream colour – one of these is a ram, police said.
The females are all said to be in lamb.
They are described as smaller than traditional-size sheep and they all have ear tags fitted with unique numbers.
The theft is believed to have taken place between 10am on Monday, November 28 and 10am on Wednesday, November 30.
Anyone with information is urged to call Lincolnshire Police on 101 quoting incident 184 of November 30.