Russian state pollster VTsIOM put President Vladimir Putin 's United Russia on 44.5 percent, ahead of the ultra-nationalist Liberal Democratic Party on 15.3 percent, the Communists on 14.9 and A Just Russia on 8.1.
"We can confidently say that United Russia has won," Prime Minister Dmitry Medvedev said on state television, adding that the party would have an "absolute majority" in the new legislature.
The four leading parties -- which made up the last parliament and all back the Kremlin -- were the only ones that cleared the five percent bar to claim half the seats up for grabs.
After a change to the election law the other half of the deputies in the 450-seat legislature are being elected on a constituency basis, with the pro-Kremlin parties also expected to dominate.
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Opposition party Yabloko received 3.5 percent of the vote , missing the threshold required to enter parliament.
The Parnas opposition party, headed by former prime minister Mikhail Kasyanov, got 1.2 percent of the vote .
The turnout of the vote three hours before polls closed stood at just under 40 percent, significantly down from the last parliamentary elections in 2011.