Tens of thousands of people gathered in the Russian capital, Moscow, on Saturday to protest the exclusion of opposition and independent candidates from the city council vote.
It is the fourth consecutive weekend of demonstrations to protest the exclusion.
Among those barred from running are allies of top Russian President Vladimir Putin critic and opposition politician Alexei Navalny.
The White Counter, an NGO that tracks participants in rallies, counted 49,900 participants, while Moscow police said the figure was closer to 20,000.
The OVD-Info protest monitor said on social media that Russian police detained 72 people on Saturday over opposition protests staged in several cities.
The monitor said 55 people had been detained in St. Petersburg, 10 in Moscow and seven in Roston-on-Don.
Unlike the previous protests, the Saturday gathering in central Moscow was approved by city authorities. In the earlier demonstrations, thousands of people were detained, sometimes violently.
Protesters carried placards with slogans such as "Give us the right to vote!" and "You've lied to us enough," while others held up pictures of activists arrested at earlier protests.
Opposition politician detained
Police on Saturday detained Lyubov Sobol, an unregistered candidate who has become a leading figure of the protests.
Most opposition candidates who have been banned from participating in the vote have been jailed for violating protest laws.
Although Saturday's rally was authorized and participants should not face detention, Navalny, who is currently in jail, called for supporters to walk peacefully through the city.