Lawyers have boycotted courts across Pakistan in protest at President Musharraf's suspension of the country's top judge for alleged misuse of office.
In Lahore, more than 20 lawyers were injured in clashes with police. Hundreds of lawyers wearing black suits rallied in other cities.
They say the removal of Chief Justice Iftikhar Mohammed Chaudhry is unlawful.
The judge is a controversial figure noted for his firm line on government misdeeds and human rights abuses.
Witnesses said the demonstration was one of the largest ever by High Court lawyers in Lahore.
They were marching down a main road when police used batons to try and break up the procession.
More than 20 lawyers were injured although none of the injuries appeared life-threatening.
Rallies attended by hundreds of black-suited lawyers were also held in the capital, Islamabad, and in other cities including Karachi and Quetta.
The Bar Association says the court shutdown is total.
"It's a complete boycott of the superior and lower courts by all lawyers," Court Bar Association president Munir Malik told the AFP news agency.
The BBC's Barbara Plett in Islamabad says the clash in Lahore reflects growing tension in the country since President General Pervez Musharraf removed the chief justice from his post on Friday.
The president had received "numerous complaints and serious allegations for misconduct, misuse of authority and actions prejudicial to the dignity of office of the chief justice of Pakistan," the state-run Associated Press of Pakistan news agency reported.
Lawyers, opposition parties, human rights activists and some judges have condemned the move as unconstitutional and a blow to the independence of the judiciary.
The president says he has referred Mr Chaudhry's case to a judicial panel. The government has so far not made public details of the allegations.
Our correspondent says the chief justice had an abrasive style and had earlier been publicly criticised by a lawyer for abusing his authority.
Chaudhry: Chief justice since 2005
But she says many in the legal community believe Iftikhar Chaudhary was dismissed because he took up cases unpopular with the government.
Chief among these was a petition to recover missing persons, allegedly abducted by intelligence agencies. He also overturned the recent sale of Pakistan's state-run steel mills.
The president is also accused of trying to intimidate the judiciary in an election year.
Ikram Chaudhry, former president of the Supreme Court Bar Association, told the BBC's Urdu service: "General Musharraf is trying to bulldoze the judiciary. He wants to leave no stone unturned."
He said Iftikhar Chaudhry was to all intents and purposes being held under house arrest in Islamabad, with a police guard posted at his residence and the official flag taken down.
Only a few visitors have been allowed in to see Mr Chaudhry since he was suspended.
The current president of the Supreme Court Bar Association said he had been told by Mr Chaudhry that he would defend himself and would not step down.