John Ryan, 44, from Barrett’s Place in Macroom, Co Cork, was last seen in the town centre at about 9.50am last Friday.
It is thought Mr Ryan, who is single and lives alone, boarded a bus to Cork from Macroom’s main street at 10.15am and may have disembarked outside Cork University Hospital shortly after 11am.
Mr Ryan was also seen in the Macroom branch of Dunnes Stores on Thursday night, where CCTV images show him wearing a dark navy thigh length jacket and dark trousers.
Mr Ryan is of average height and build, has green eyes, tight, dark brown hair and a dark moustache.
He has a distinctive home-made heart-shaped tattoo in blue ink on his right forearm with the name “Ian” tattooed inside it.
Mr Ryan wears a small round sleeper-style earring in his left ear.
Gardaí have urged anyone with any information to contact Macroom Garda station on 026-20590.