Fine Gael TD Brian Walsh has said he will not be contesting in the next general election.
In a statement tonight, Mr Walsh said he would not be seeking re-election due to medical advice.
The 43-year-old said recent health problems were likely to relapse or worsen, and he was making the decision with deep regret.
His withdrawal follows months of speculation locally as to whether he would stand in the 2016 election.
It leaves outgoing Deputies Sean Kyne and John O'Mahony along with Senator Hildegarde Naughton as the party's three representatives in Galway West next time round.
Mr O'Mahony has moved from the neighbouring constituency of Mayo, after boundary revisions saw a chunk of territory in south Mayo transferred to an expanded Galway West.
Mr Walsh's decision not to stand will increase Mr Mahony's chances of winning a seat.
The reduction in the number of candidates also leaves Fine Gael without a Galway city based contender in the general election.
Mr Walsh said: "I have informed An Taoiseach Enda Kenny of my decision, and I would like to thank him for his support throughout my political career and, in particular, his understanding and support in recent days."
First elected to Galway City Council in 2004, Mr Walsh was one of two Fine Gael TDs elected in Galway West at the last election.
It was the first time the party had returned two Deputies in the constituency since the early 1980s.
He lost the party whip in 2013 after he voted against the Protection of Life during pregnancy bill.
He was readmitted some months later, having voted with the coalition, while he was outside the parliamentary party.