No candidate has secured an outright victory in Sunday's presidential election in Guinea-Bissau, the electoral commission has said.
A run-off vote between the top two contenders will be held next month.
Jose Mario Vaz, an ex-finance minister from the main PAIGC party, will face Nuno Gomes Nabiam, a military-backed bureaucrat running as an independent.
The general elections were the first since a coup in 2012, after which the EU and others suspended aid donations.
Guinea-Bissau has a history of coups and no elected leader has served a full term since independence from Portugal in 1974.
Guinea-Bissau is one of the poorest countries in the world and has been further destabilised by the booming trade in illegal drugs from Latin America, in which the country is used as a staging post for the European market.
More than 80% of the electorate turned out to chose from 13 presidential candidates and 15 parties fielding candidates for parliament.