Tens of thousands of people rallied against anti-corruption legislation in Romania's capital Bucharest, braving heavy snow, as well as a large police presence.
The protests were organised on Saturday after the leftist-leaning, ruling Social Democrats (PSD) passed new legislation last month that critics say will make it harder to prosecute crime and high-level corruption.
President Klaus Iohannis, who is a critic of the bills, still needs to sign them into law.
An estimated 50,000 people marched from University Square to the parliament building.
"I came here to live in a free country that is not full of corrupt people," Puica Marinescu, a protester, told Al Jazeera. "I want these assassins and mafia people who confiscated the revolution to leave the country."
Another protester, Alexandra, said: "I come here because we want to correct politicians and justice in Romania."
The protesters briefly scuffled with riot police in Bucharest. There were smaller protests in the cities of Cluj, Timisoara, Constanta, Bacau, Sibiu and Iasi.
Rule of law
The European Union has spoken out and urged Romania to do more to prevent and tackle high-level corruption.
Romania joined the EU in 2007 and is subject to special monitoring of the judiciary and the rule of law.
More than 90 Romanian former ministers, deputies and senators have been indicted by the Council of Europe's anti-corruption unit since 2006.
But Brussels has been accused of being too soft on the former communist state.
The scale of the protest is nothing new in Romania's history. Tens of thousands took to the streets in 1989 in a mass uprising, which led to the downfall of the communist leader Nicolae Caeusescu.
Memories of that revolution seem rife nearly 30 years later. "No communists, no criminals, no corrupts," one of the banners read in English at Saturday's demonstration.
New prime minister
The protest march followed another eventful week in Romania when Iohannis spoke out after a second failed government saw another prime minister removed.
"After I weighed all the arguments, taking into account the actual situation in parliament, I decided to give the PSD one more chance and to designate the person they proposed, Mrs [Viorica] Dancila," Klaus said.
Danchila, who is a member of the European Parliament and the first woman to be nominated, will be the third prime minister in 11 months.
She is considered to be a very close ally of the PSD leader Liviu Dragnea, who was convicted of ballot-rigging and faces charges of abuse of office. His two-year prison sentence was suspended.
If the current anti-corruption legislation is enacted, the case against him would be dropped.
Danchila was brought in after her predecessor stepped down on Monday after falling out with the party head.
The new prime minister is set to be sworn in on February 2. One of her first tasks could be appeasing the marchers.
