A power-sharing agreement broke down in July, prompting the election
The people of Guinea-Bissau have voted in parliamentary elections that were seen as a major test of its stability.
International observers said there had been a high turnout and that voting had been calm and orderly. Official results are not expected until next Friday.
Four parties are expected to dominate the poll, including the new Republican Party for Independence and Development.
The former Portuguese colony has had a history of coups since independence, and has become a drug smuggling hub.
Last month, UN Secretary-General Ban Ki-moon warned that drug trafficking could wreak havoc in the West African nation, and called for the Security Council to consider imposing sanctions on those responsible.
The head of the European Union's observer team, Johan Van Hecke, told the BBC that the drug trade had been a major campaign issue.
"There have been some very inflammatory statements made by some political leaders accusing each other of being directly or indirectly involved in drug trafficking, and for accepting money from people who are responsible for drug trafficking to fund their campaigns," he said.
Speaking after polls closed on Sunday, Mr Van Hecke said his fellow monitors estimated the turnout had been between 70% and 80%.
"The day unfolded calmly and orderly without tension or intimidation." He told a press conference in the capital, Bissau. "No incidents were reported."
The historically dominant African Party for the Independence of Guinea-Bissau and Cape Verde (PAIGC) is expected to win the most seats in the National Assembly when the official results are announced next week.
However, observers say it will face stiff competition from the Republican Party for Independence and Development (PRID), which was formed ahead of the vote by former Prime Minister Aristides Gomes, an ally of President Joao Bernardo Vieira.
The Social Renewal Party (PRS) and the Development, Democracy and Citizenship Party (PADEC) are also expected to do well.
After casting his vote, President Vieira declined to declare which party he supported, but vowed to work closely with the winners.
"We are all going to unite to support this party to govern and develop the country," he said.
The BBC's West Africa correspondent, Will Ross, says a relatively smooth polling day does not necessarily mean a job well done - disputes and violence have accompanied the announcement of results in past elections.
Sunday's vote was almost entirely funded by the international community, which is concerned that further political turmoil could see Guinea Bissau slide further under the influence of drug traffickers.
The fact that many civil servants have not been paid for months is a sign of how the politicians have been failing the population, our correspondent says.
In recent years there have been frequent changes of government, and observers say the ideal result could be for one party to gain a clear majority.
Our correspondent says that in the past no single party has managed to secure power outright, which has led to a series of coalition governments plagued by splits and acrimony. Since coming to power in 2005, President Vieira has had three prime ministers.
The country has been in political limbo since July, when a power-sharing deal signed last year broke down and there were reports of yet another attempted coup, he says.
The people of Guinea Bissau hope their country is finally turning its back on the coups and political chaos which have helped keep the country one of the very poorest in the world, he adds.