Daniel Walsh was 61 when he went missing and would be 75 now.
He is described as 5 foot 8 and had a thin build, long grey hair, a beard and moustache when last seen.
Danny worked for the City Council prior to his retirement in 2006.
Gardaí are looking to make contact with two men who are understood to have lived with Danny at a house in the Elton Lawn area of Bishopstown around the time he was reported missing.
Anyone with any information is asked to contact Gardaí in Togher on 021 494 71 20.
