Bahrainis voted for a new parliament at a time of rising sectarian tension in the Gulf state, where decision-making is tightly controlled by its rulers.
Polling stations closed at 6pm Irish time, and results were not expected until tomorrow.
The main Shia opposition group Wefaq said it expected to win all 18 seats it had contested, based on its own exit polls. There are 40 seats in Bahrain's parliament.
The run-up to the vote was overshadowed by a broad security crackdown against some Shia opposition groups in August that also targeted bloggers and human rights activists.
Next week, 23 men charged with plotting to overthrow the political system will appear in court for the first hearing in their trial.
Critics accuse Bahrain of apportioning its voting districts in such a way as to ensure the Shia opposition will not have a majority in parliament.
Today’s election was the third since the creation of the current parliament, which has limited powers since bills need to pass an upper house whose members are appointed by the king.
Some districts where candidates fail to win 50% of the vote could see a second round of polling next Sunday.
About 318,000 Bahrainis are eligible to elect the 40-member parliament, while the king names the members of a 40-strong upper chamber, known as the consultative council.
Parliament has the authority to examine and pass legislation proposed by the king or cabinet and also has monitoring powers, while the consultative council has the power to block legislation coming out of the lower house.
