Officers from Inverell's Rural Crime Prevention Team are investigating the theft of 22 Merino ewes recently.
Police believe the mob of 22 merino ewes was stolen from a paddock on Baldersleigh Road near Guyra in the weeks leading up to August 26.
The sheep are a 2016 or 2017 drop, with full wool and are currently in lamb.
Each sheep had either a black or white ear tag with PIC numbers NA025488 or NG023969 on them.
The sheep also have a distinctive ear mark of a diagonal slash out of the bottom and top of the near side ear.
Police say the ewes are expected to give birth to lambs in the coming weeks.
Officers from Inverell's Rural Crime Prevention Team are urging anyone with information regarding the missing sheep, or who saw anyone acting suspiciously in the Baldersleigh Road area to come forward.
Investigators are also urging all landholders to report stock theft, regardless of the number of stock stolen.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000, or Inverell's Rural Crime Prevention Team on 6722 0530.