Russian authorities have detained dozens of protesters at rallies demanding that President Vladimir Putin should not seek re-election next year.
At least 30 people were reported to have been held in St Petersburg and more than 16 in the southern city of Kemerovo.
Activists in some other cities were kept away from protests, reports said.
President Putin has not confirmed that he will run in March 2018 but he is widely expected to do so.
The rallies - held under the slogan "We're sick of him" - were organised by the Open Russia movement founded by former oil tycoon Mikhail Khodorkovsky.
Mr Khodorkovsky, a fierce critic of President Putin, lives in exile after spending 10 years in a Siberian prison on fraud charges, which he says were politically motivated.
Protesters also held an unauthorised rally in central Moscow on Saturday, but the presidential reception office, to which they planned to submit letters, was blocked off.
A journalist with AFP news agency in St Petersburg said about 200 people had gathered for the rally and at least 30 protesters were taken away by authorities.
Open Russia put the figure at about 50 people while OVD-Info, which monitors the detentions of political activists, said more than 125 had been detained. Police did not release official figures.
"Putin is an usurper. He has to finally go. We're sick of him," said one protester in St Petersburg, quoted by AFP.
"Everything is bad. Education, health - everything has been destroyed. I want changes," said another.
The protests come days after Russia opposition leader Alexei Navalny was taken to hospital when a green antiseptic solution was splashed in his face.
Mr Navalny is one of Russia's foremost critics of President Putin and has announced his intention to run for president himself.
However, a conviction for embezzlement - which he denies - would bar him from running for office.
Mr Putin has been a dominant political figure in Russia since his election as president in 2000.
He served two terms and then a four-year stint as prime minister, before resuming the presidency in 2012.