Glenrothes MP Lindsay Roy is to stand down at the next general election.
Mr Roy, 64, who has represented the area since 2008, announced this week he will not seek re-election in 2015.
The news follows the announcement last month by North East Fife MP Menzies Campbell that he will also retire in two years.
Mr Roy, who is a former high school rector, secured the Glenrothes seat for Labour in a by-election following the untimely death of sitting MP John MacDougall.
The by-election success was followed by an overwhelming victory in the 2010 general election, when he more than doubled his majority to more than 16,000, polling almost three times more votes than his nearest challenger.
Mr Roy was rector at Inverkeithing High School for 19 years and had a short spell at the helm of Kirkcaldy High before entering politics. He was awarded the CBE for services to education in Scotland in 2004.
Announcing his decision to retire, he said: “I have spent more than four decades in public service, both in education and politics, but I have decided that I will stand down at the next election.
“Most people would count themselves fortunate to have one career where they get enormous job satisfaction I have been privileged to have two.
“However, all good things must come to an end and I have decided it is time to stand down.”
Mr Roy is now looking forward to spending more time with his wife Irene and his children and grandchildren.
He added: “Although I have decided not to seek re-selection as the Labour candidate for Glenrothes, I want to stress that I will maintain my commitment to do my best for all my constituents until a new Westminster representative is elected in 2015.
“There will be no winding down ahead of the General Election and I will continue to give this privileged position the input it demands.”