Election officials in Sao Tome and Principe say they will try to hold a new round of balloting in parts of the country where some people were blocked from getting to polling stations on Sunday.
According to witnesses in Sao Tome and Principe, angry voters blocked roads in several districts, hindering voters from getting to some polling stations.
The president of the National Election Commission, Jose Carlos Barreiros, said about 10,000 registered voters were unable to vote.
He added that they would try to ensure these people had the opportunity to vote this week. This means that results will probably not be available for another week.
Eighty thousand people were eligible for Sunday's vote, but there are no final figures on turnout.
Some protesters said they boycotted the vote because politicians have failed to provide basic services such as electricity, water, and road maintenance in the West African island state.
A Portuguese journalist there, Antonio Santos said many residents felt politicians were not performing basic duties.
"They boycotted because they wanted better access to the countryside, stability in the electrical light distribution, and they also say they do not have any kind of [clean] water to survive on," said Santos.
Santos said that voting had been calm, apart from the blockades. There had been no major incidents, he said.
Sao Tome gained its independence from Portugal in 1974 and mirrors its political system. A powerful president appoints a government from a separately elected parliament.
The center-left MLSTP-PSD party currently forms the government, occupying 24 of the 55 assembly seats.
But President Fradique de Menezes supports the opposing MDFM-PCD party, which holds one seat less.
The election campaign had revolved around mutual allegations of corruption between the main parties. The president has sacked several prime ministers in past years over corruption allegations.
Exploration of Sao Tome's considerable oil reserves began last year. Competing politicians promised voters drinking water, electricity, and better health and education. But the country has yet to draw any benefit from the oil.
Political analyst Chris Melville said this has caused major disappointment with Sao Tome's citizens.
"It would seem that a significant proportion of the population has become extremely frustrated with the political process and with the system of multi-party democracy that Sao Tome has. And they no longer have any confidence in the major parties, but are faced with little other choice about who to vote for. And this is of serious concern for the country," said Melville.
Melville explains that political problems do not bode well for companies looking to exploit Sao Tome's oil reserves.
"This kind of political instability has deterred to differing degrees interest from the oil majors," he added. "When you have a country such as Sao Tome whose political system is unstable and prone to frequent little storms in a tea-cup, you have a situation where the development of these off-shore fields becomes increasingly difficult."
The election is being taken as a measure of the popularity of President Menezes, who faces re-election in September.