With no candidate expected to win a majority, the vote may only decide the final players for a run-off in late May or early June.
Political newcomer Ollanta Humala, aged 43, a retired army lieutenant colonel, has promised to spend more on the poor and take on Peru’s elite. He has aligned himself with populist firebrand leader Hugo Chavez of Venezuela.
Former congresswoman Lourdes Flores hopes to replicate the triumph of socialist Michelle Bachelet, who was elected as neighbouring Chile’s first woman president in December.
The third major candidate is former president Alan Garcia, whose 1985-1990 administration ended in violence, food shortages and inflation exceeding 7,000%.
The incumbent president, Alejandro Toledo, who by law can’t run for a second consecutive term, called on Peruvians to ensure they don’t elect someone who would usher in “the authoritarianism and instability we’ve known in the past”.
Mr Humala’s early lead in the polls has withered and the three candidates are running neck-and-neck.