Polling stations have opened in the Russian capital,
Eleven parties are competing for places in the lower house, the Duma - though it is not clear how many will secure the 7% needed to qualify for seats.
President Vladimir Putin's party is predicted to win, boosting his bid to retain power after leaving the Kremlin.
Opposition parties have accused the government of stifling their campaigns.
Independent monitors say their attempts to observe the poll have been hampered.
The Organization for Security and Co-operation in Europe (OSCE) has abandoned its plans to send a big team of election observers to
Only a much smaller group of MPs from the OSCE's parliamentary assembly will be in attendance.
That means just 330 foreign monitors will cover 95,000 polling stations.
The British ambassador in
The largest party in the Duma going into the elections is United Russia, and it will be hoping to maintain its dominance against the challenge from the Communist Party, the Liberal Democratic Party, the Yabloko party and others.
Putin is at the top of the United Russia party list - opening the possibility that he could keep a grip on power from parliament even after stepping down as president next year.
Within
Eastern start
Voting began at 0800 on Sunday (2000 GMT, Saturday) in
Voting is not set to end until 22 hours later, when polls are due to close in the enclave of
The BBC's Richard Galpin, in the Siberian city of
In
Sailors in the
"I'll vote for United Russia," Vladimir Babikov, 19, told the AFP news agency.
"They've done a good job, everything is getting better."
In Petropavlovsk-Kamchatsky, Alexei Gutkin, a 42-year-old engineer, voted for the centre-right Union of Right Forces.
"United
'Farce'
The run-up to the vote has been marred by increasing allegations that the poll could be rigged.
Correspondents say more and more ordinary people have been speaking out in interviews with the mainstream media about how they have been pressured to vote for United Russia.
Opposition rallies have been broken up, parties have complained that their headquarters have been raided, and that state media has been a mouthpiece for the government.
The former chess grandmaster and Kremlin critic Garry Kasparov has dismissed the elections as a "farce". His political grouping is one of several to be barred from contesting the poll.
More than 100 million voters are eligible to cast ballots at 95,000 polling stations across the country, with about 450,000 police officers reportedly on duty to ensure order.
An officer casts his ballot in a polling station at a Russian army base in