Donal Greene (22) was last seen at Derryhassan, Ballyconnell in County Cavan at approximately 5am last Saturday, February 28.
He is described as being approximately 6’ 3” in height and of slim build.
When last seen the 22-year-old was wearing a white shirt and black trousers.
Gardai are concerned for Donal's welfare and are appealing for anybody who may have information regarding his whereabouts to come forward.
Anyone who has seen Donal or who can assist in locating him is asked to contact Ballyconnell Garda Station on 049-952 6102, the Garda Confidential Telephone Line 1800 666 111 or any Garda Station.