Thousands of people around Russia have joined unauthorised rallies to protest against the detention of jailed opposition leader Alexei Navalny.
They are calling for Navalny, who has been on hunger strike for weeks, to receive proper medical care. More than 1,000 people were reportedly arrested.
Navalny, 44, was jailed in February and is demanding medical attention for acute back pain and leg numbness.
The largest protest was in Moscow, but others took place in major cities.
These included St Petersburg, Vladivostok in the Far East, a number of cities in Siberia, and the central city of Vladimir where Navalny is being held.
The opposition had hoped Wednesday's protests would be the largest in years, but reports suggest they have been smaller than those that took place shortly before Navalny was jailed.
More than 14,000 people protested in 29 cities, police said. This included 6,000 people who gathered in Moscow.
But estimates from monitoring groups tend to far exceed official police figures. One such group, OVD-Info, said more than 1,000 people had been detained nationwide.
'Fight for the future'
"This is one of the last gasps of a free Russia," one protester told Reuters news agency. "We came out for Alexei."
"This is a fight for the future," another demonstrator, Andrei Zamyatin, told AFP.
Others were less hopeful about the impact the mass action could have. "I don't think this protest can save Navalny," Alexander Butuzov told AFP.
"There would need to be at least 200,000 to 300,000 people in the streets," he said.
The protesters defied stark warnings from the authorities and a heavy police presence in most major cities.
"Any aggressive actions by participants in unauthorised public meetings, especially attempts to provoke clashes with law enforcement officials, will be regarded as a threat to public safety and immediately suppressed," the interior ministry said earlier this week.
In Moscow, riot police urged people to leave the protest area and formed barricades to try and contain the demonstrators' route.
They earlier cordoned off the area around Manezh exhibition hall, where Mr Putin addressed both houses of parliament during his annual state of the nation speech.
It's hard to tell the size of a rally when crowds are banned from gathering in one place, and that's the point. In Moscow, protesters were constantly diverted by police, as roads were closed.
Fewer came out than in January when Alexei Navalny was arrested - but that's hardly surprising. The price of protesting is rising in Russia: you face a beating, losing your job - at worst, a prison sentence.
Many of Navalny's supporters who did make it out on Wednesday said they were afraid, but they were passionate: in Moscow, they shouted for Navalny's freedom and they called Vladimir Putin a killer.
For once, the police stood back and let them march - no dragging screaming protesters into their vans.
In St Petersburg it was different: hundreds were arrested there, some stunned with electric shockers by police.
Team Navalny are claiming success. But their goal was to get him released, or at least get him a doctor, and the Kremlin is unlikely to be persuaded by Wednesday's crowds.
On Monday, Navalny was moved to a prison hospital where the authorities said his condition was "satisfactory".
The FSIN prison service added that he was being examined by a doctor daily and had agreed to take vitamins.
But Navalny's doctors warned he would "die within the next few days" if not given urgent medical attention for his back pain and leg numbness.
He started a hunger strike on 31 March in protest at not being able to see his own medical team. His doctors say recent blood test results indicate he could suffer kidney failure and go into cardiac arrest at any moment.
Western countries say Navalny was poisoned with a nerve agent last August and only narrowly survived. After his transfer to intensive care in Berlin, toxicologists concluded that the poison was Russian weapons-grade Novichok.
The West blamed the Russian state for the attack, and Navalny accused President Vladimir Putin directly. The Kremlin denied any involvement and disputed the conclusion about Novichok.
Navalny was jailed in February for violating the terms of a 2014 suspended sentence for fraud. He says the case is politically motivated.
The European Court of Human Rights found violations of justice in the case against him.