Battleground seat North East Fife held by Willie Rennie with a majority of 3,465, is being tallied at the Michael Woods Sports Centre in Glenrothes.
Cowdenbeath and Kirkcaldy are being totted up at Fife Council's Rothesay House offices, also in the town.
North East Fife was won from the SNP in 2016 by Rennie, but early polling suggests it could be a close-run race between the Liberal Democrat leader and SNP candidate Rhuaraidh Fleming.
Since the last Scottish Parliament election, the North East Fife UK parliament seat has swung between the nationalists and the Liberals, famously by just two votes in 2017.
Cowdenbeath, with a similarly slim SNP majority of 3,041, is a five-way contest between the SNP, Labour, Conservatives, Liberal Democrats and the Scottish Greens.
Kirkcaldy is also torn between five candidates from Labour, the Lib Dems, Tories, SNP and the Scottish Libertarian Party, fielding Calum Paul as one of their nine constituency candidates across Scotland.
Results are expected between 4:00pm and 6:00pm for all three seats. Tomorrow, Mid-Fife and Glenrothes will be counted at Rothesay House while Michael Woods will host the tallies for Dunfermline and the Mid-Scotland and Fife region.