Nearly 2,000 people gathered in central Moscow on Sunday demanding freedom of assembly in a rare sanctioned rally.
The Russian opposition protests on the 31st day of each month are a nod to the 31st Article of the Russian constitution, which guarantees the right of assembly.
Opposition activists gathered to protest in two separate rallies Sunday after Moscow City Hall gave a rare approval for the rally but placed a cap on the number of participants at 1,000 people, down from the requested 1,500.
Supporters of veteran rights activist and chairman of the Moscow Helsinki Group Lyudmila Alexeyeva agreed to the limit. But rally co-organizer Eduard Limonov slammed the decision as a "betrayal."
Limonov's supporters rallied Sunday, separated from Alexeyeva by a police cordon. Police later allowed them to merge with the sanctioned protest.
"Authorities have shown respect for the law for the first time," Sergei Udaltsov, leader of the anti-Kremlin Left Front movement, said as he moved to join Alexeyeva's rally "It's a big victory for the opposition."
Uncharacteristically for such protests, there were no reports of police violence.
Popular support for vocal opposition groups is minimal in Russia, and their activities have been thwarted in regions like Moscow, where authorities ban their rallies and police regularly break up their gatherings.
Associated Press writer Nataliya Vasilyeva and photographer Sergei Ponomaryov contributed to this report.