A 38-year-old man from Sleaford has been missing from his home since January 18.
Anthony Moss of Truro Close, Sleaford, is described as around 5ft 10in tall, of medium build, with short brown hair and a beard.
He was last seen wearing a light green jumper and grey trousers.
Police are appealing for Mr Moss to get in touch, or for anyone who has any information on his whereabouts, to call as soon as possible.
Mr Moss has links to the Peterborough area and it is thought he could be there.
Anyone with any information can contact Lincolnshire Police on 101.