Police are appealing for any information on the whereabouts of 76-year-old Derek Witten.
Derek is missing from his home in St Dustans Close, Kettering, and is believed to be in the London area.
He is described as a slim white man, about 5ft 3in, with grey, thinning hair and hazel eyes.
He drives a silver Ford Fiesta, registration number Y735 TOC.
Officers are asking anyone who sees Derek or knows of his whereabouts to contact Northamptonshire Police on 101 or they can call the independent charity Crimestoppers anonymously on 0800 555111.