According to surveys, there is a difference of about one percentage point between the candidates, with Fujimori holding a small lead.
The election results are expected to take several weeks.
Conservative Keiko Fujimori is making her fourth attempt to become president. She is haunted by the legacy of her father, the authoritarian, effectively deposed and imprisoned President Alberto Fujimori.
Roberto Sánchez, who is running for the third time, is accused of cheating over party contributions and risks being put on trial.
