Over 46 percent voting took place in Mirzapur, Chandauli and Robertsganj.
In Robertsganj, around 43 percent votes were cast by 3 p.m, while in Mirzapur, a seat left by the Bharatiya Janata Party (BJP) to its ally Apna Dal, there was 45 percent turnout.
BJP's national president Rajnath Singh hails from Mirzapur.
In Chandauli too, the voting percentage increased manifold since the last election, an official said.
Fearing strikes by Maoists on polling parties or voters, the Election Commission has ordered polling to be over by 4 p.m. in these three constituencies as a precautionary measure.