Gardaí are seeking the public's help to find Mr Brian Simpson (48) from Sherwood Park, Mullingar, Co Westmeath.
He was last seen in Mullingar at 2.45 a.m. on Saturday. He is described as being of six feet, two inches high; of strong build; with short brown hair and blue eyes.
He is originally from Enniskillen and has a Northern accent. When last seen, he was wearing a purple polo shirt, blue jeans and tan-coloured desert boots.
Anybody with information is asked to contact Mullingar Garda station on 044-84000.