Bulgarians are voting in their fourth general election in less than two years amid anxiety over soaring consumer prices and energy costs.
Sunday’s vote started at 7 am (04:00 GMT) and will end at 8 pm (17:00 GMT).
Exit polls will be released after the ballots close, with the first partial official results expected in the early hours of Monday.
Stable government has eluded the country amid deep division within the political elite over how to tackle entrenched corruption.
Aljazeera said opinion polls suggest that up to eight political parties may enter the next parliament, with the centre-right GERB party of former long-serving premier Boyko Borissov, leading with about 25 to 26 percent of the vote.
Just as last year, Borissov is widely expected to struggle to find coalition partners among his major rivals who accuse him of allowing corruption to fester during his decade-long rule, which ended in 2021.
Turnout is expected to be low with many voters angry over political infighting.