The leftist candidate is fighting a close battle with three others: a centrist former president, the daughter and heir to former president Alberto Fujimori and a liberal former banker and prime minister. AFP draws mini profiles of cadidates:
- Ollanta Humala, now closer to Lula than Chavez?
For the second time in five years the energetic, retired lieutenant colonel leads the race for the presidency with a left-wing, nationalist line, drawing popular support from many poor in the Andean provinces.
Humala won the first round in 2006 but was beaten in the second by current President Alan Garcia, who warned that his opponent would bring radical change.
Humala paid for his outspoken admiration of Venezuelan President Hugo Chavez, the leader of Latin America's anti-liberal left. Chavez's loud support was no help.
But Humala, 48, has now transformed his act, exchanging a red campaign T-shirt for a white one or even a suit in talks with investors or church leaders.
"Peru has changed and I've changed," Humala says, still showing anger at a rapidly-growing Peru where "a few possess a lot, and a lot possess a little."
He has sought to reassure nervous investors with promises of careful fiscal policy, respect for Peru's free trade deals and no plans to seek re-election -- a growing trend on a continent still haunted by dictatorships.
Humala now looks to moderate leftist and former Brazilian president Luiz Inacio Lula da Silva for inspiration, while distancing himself from Chavez.
"I'm not like Chavez," he said recently. "Venezuela's model is not applicable in Peru."
Peru's stock exchange and currency, the sol, both shuddered when Humala rose to the top of opinion polls two weeks ago.
Many critics say he is a "wolf in sheep's clothing," and that Chavez's state socialism and authoritarianism overshadow his campaign.
It would be a challenge for Humala to beat a more centrist candidate in a second round. Latest polls give him a favorability rating of 24.4 percent to 28.7 percent.
- Alejandro Toledo, the return of the Indian
The 65-year-old is seeking a "second chance" to tackle unfinished business, five years after the end of a presidency remembered for economic growth and political stability following the turbulence of Alberto Fujimori's leadership.
The former shoe shiner and street seller, who was born into Andean poverty, was Peru's first Indian president and never forgets to remind his compatriots -- more than 80 percent of whom have Indian roots -- of his background.
Toledo calls himself a "statistical error" for having received a university grant as a boost to a subsequent career as an economist and professor in the United States, where he has lived for most of the past five years.
Following his brave opposition to the autocratic end of Fujimori's regime, Toledo's presidency sought peace and oversaw growth, free trade deals and a Truth and Reconciliation Commission after two decades of political violence.
But his mandate also left a sense of frivolity, a taste for fine living which his rivals now mock, the tardy recognition of an illegitimate daughter and corruption scandals among those close to him.
Toledo has something for everyone, from indigenous blood to an American CV and a flawless management record that could benefit him in a second round against a less consensual rival.
Latest polls give him a 16.1 to 20.4 percent favorability rating.
- Keiko Fujimori, in the shadow of her father
The youngest of the hopefuls, at the bottom age limit of 35, Keiko is the assumed heir to the politics of her father, the iron-fisted president of the 1990s who is now in jail for crimes against human rights.
Keiko Sofia Fujimori already took over as a young "First Lady" of Peru aged only 19, following her parents' divorce.
She is now a popular lawmaker -- with the best results of all lawmakers in 2006 elections -- who has managed to preserve fujimorist support, keeping around 20 percent of the electorate.
Keiko has capitalized on the positive image her father still holds for having beaten both hyperinflation and leftist Shining Path guerrillas in the 1990s, despite a terrible social cost and bloody repression.
"I'm Keiko Fujimori, daughter of Alberto Fujimori, and I'm very proud of it," she said at the end of a debate between candidates, during which she constantly associated herself with her father's legacy.
She promised the same policies and social programs, as well as reinforcing the police and army.
But she has struggled to downplay suspicions that her 72-year-old father is the brains behind her campaign and would oversee her presidency from behind bars, with the same military and business ties.
"I listen to his advice but the final decision is mine," she said recently.
Latest polls give her a favorability rating of 17.1 to 20.5 percent.
- Pedro Pablo Kuczynski, the "gringo" liberal outsider
Kuczynski, a former economist and Wall Street banker with US-Peruvian nationality, has surprised many by staying in the race, playing both on his novelty and his experience as a minister in two different Peruvian governments.
The son of immigrants -- a French mother and a German doctor famous for his work on tropical diseases -- Kuczynski insists that he is not a professional politician, a popular stance in a country lacking confidence in elected representatives.
After five years' absence from the political scene, the candidate nicknamed PPK has managed to assemble a motley coalition, from right-wing Catholics to a small evangelical party and the "humanist" left.
Tall and lanky with a jovial smile, the 72-year-old accomplished flautist has attracted young, urban voters by reaching out through the Internet and social networks.
The multimillionaire investor has also created hope of jobs and a better division of the country's wealth among poor Peruvians with whom his has little in common.
Although dubbed "El Gringo" (the American), Kuczynski has promised to give up his US citizenship if elected.
Latest polls give him 16.3 to 18.1 percent favorability.