Thousands of Russians have taken to the streets of the capital to drive Vladimir Putin, Russian president, from power.
Armed with anti-Putin slogans, Orthodox banners and black-and-yellow flags of pre-revolutionary Russia, the black-clad participants joined in the "Russian March" as Putin faces the most vocal opposition to his rule since coming to power 12 years ago.
They accused Putin of ignoring the rights of ethnic Slavs and calling an end to immigration from neighbouring former Soviet-bloc states.
Sunday's demonstrations were timed to coincide with the Day of Popular Unity, a national holiday which this year marks the four hundredth anniversary of the 1612 expulsion of Polish occupiers from the Kremlin.
Alexander Belov, one of the march's organisers, said an increasing number of people were growing disillusioned with the veteran leader.
"Putin is afraid of us," he told the rally. "He feels his time is ending because the future belongs to us. We will chase out the occupiers from the Kremlin."
Belov estimated the turnout at the march at around 20,000, while Moscow police put the number of participants at up to 6,000 and 2,500 in the rally.
During the march police detained 25 people wearing black military overcoats in the city centre.
Many participants in the march covered their faces with scarves and surgical masks, defying a new law banning masks during rallies.
Putin has been accused of neglecting the rights of the multi-ethnic country's Slavic majority and turning a blind eye to illegal immigration.
"If Putin had a drop of reason and conscience what would he do? He would stop the wave of migration," Vladimir Tor, an activist, said.
Muscovites complain of a heavy influx of poorly educated migrants from impoverished ex-Soviet Central Asia, saying the affluent capital is already over-crowded.
"I am against the lack of a visa regime with Central Asian countries," Andrei Goldin, a 38-year-old university teacher, said.
Putin himself has slammed attempts to inflame nationalist sentiments, evoking the country's multi-ethnic, multi confessional history.
Authorities have allowed the nationalists to march through the capital despite pleas from the Federation of Migrants of Russia to either cancel or postpone the event.
The Russian Federation argued the march could sow discord in the capital, especially on a day meant to promote unity.
It is the first time in several years that the authorities have allowed the march to take place in central Moscow instead of its fringes.
Smaller nationalist rallies were held in several big cities across the country.
Accompanied by top representatives of the country's main religions, Putin on Sunday laid red carnations at the Red Square monument to Kuzma Minin and Dmitry Pozharsky who helped rid Moscow of Poles in 1612.