The PSNI are appealing to members of the public to help them locate 86-year-old William Doherty who has been missing since yesterday.
Police and the family of Mr Doherty are becoming increasingly concerned for his safety.
William, who is from the Culmore Road area of Derry, was last seen at a service station at the bottom of Glenshane Road at around 4.15pm yesterday.
PSNI Inspector Catterson said "William is described as around 5' 6" tall with grey, sandy coloured hair brushed back. He wears a hearing aid, walks with a limp and uses a walking stick.
When last seen he was wearing a navy buttoned cardigan, a pink and white shirt, sandy coloured trousers and cream shoes.
William is driving a silver E320 Mercedes registration BUI 6000 and police believe he may have travelled to Belfast and then to Fermanagh, possibly crossing the border at Pettigo.
His family say William requires medication that he does not have with him and they, along with police, are urgently seeking to establish his whereabouts.
Anyone who may have seen Wiliam is asked to contact the PSNI on 04890650222 and ask for police at Strand Road police station in Derry.