Azerbaijan is voting in parliamentary elections, seen as test of democracy in the oil-rich former Soviet republic.
The electoral body says everything has been done to ensure a free and fair vote, including the marking of voters' fingers to prevent fraud.
Opposition activists and international observers have complained that the government has been intimidating, arresting and harassing opponents.
Baku has said it will act to prevent a Ukraine-style revolution in Azerbaijan. Some opposition leaders have said they will mount mass street protests - like those seen in Ukraine last year - in the event of a rigged poll.
About 2,000 candidates - including President Ilham Aliyev's wife - are standing for 125 seats in parliament, the Milli Majlis.
Sunday's vote is the first since Mr Aliyev replaced his father, a Soviet-era strongman, in 2003.