"The number of votes that could not be traced almost exceeded the number of legitimate votes obtained by politicians.
An independent commission recommended Monday canceling results of Haiti's first-round presidential elections held in October, saying they were marred by fraud.
"It would be fair and just that, at least as far as the presidential elections are concerned, the process is relaunched from scratch," commission president Francois Benoit said.
"The number of votes that could not be traced almost exceeded the number of legitimate votes obtained by politicians."
Haiti has been mired in a deep political crisis since the election process was halted in January amid violence.
The opposition at the time claimed ex-president Michel Martelly had backed an "electoral coup."
The presidential election has been repeatedly postponed, with the most recent vote, scheduled for April 24, never materializing and officials setting no new date.
Interim President Jocelerme Privert was elected in February for three months to oversee the April run-off as well as partial legislative and local elections. He was slated to hand over power on May 14.