Tens of thousands of opposition supporters have marched through Moscow in the first major protest against President Putin in three months.
The opposition says December's parliamentary elections were fraudulent and dispute his re-election in March.
Demonstrators also demanded the release of the jailed members of the punk band Pussy Riot.
Mr Putin introduced legislation in June that increased fines for breaking laws governing protest.
Saturday's demonstration was approved by the authorities and thousands of police lined the route.
The BBC's Daniel Sandford in Moscow says this is the sixth big march there in less than a year, and while not as numerous as some others, it shows the mood against Mr Putin is still strong in the city.
Marching through the city, demonstrators shouted "Russia without Putin", and "free our political prisoners".
Some activists carried balloons with balaclava masks painted on in support of Pussy Riot, who wear the headgear when they are performing.
Three of the band's members were convicted of hooliganism and jailed for two years in August after staging an anti-Putin protest in a Moscow cathedral in February.
Their sentence was criticised by the US, UK and EU as being "disproportionate".
'Crooks and thieves'
Addressing the crowd, prominent opponent Alexei Navalny urged protesters to keep up the pressure on the authorites.
"We must come to rallies to win freedom for ourselves and our children, to defend our human dignity," he told a cheering crowd.
Another opposition leader, Boris Nemtsov, said many people disagreed with the way Mr Putin and his party were running the country.
"We came to say a definite 'No' to the crooks and thieves. We came to do everything to stop repression. We came to do everything to have new, fair elections," he said.
Mr Putin has taken a tough line against the opposition since he began a third term as president this year.
He approved legislation increasing fines for those who violate protest laws in June.
Anyone participating in an unsanctioned rally, or damaging property during a sanctioned rally risks a fine of about $10,000 (£6,440).
Source: BBC News