Tight security was in place early amid fears of renewed confrontation as Pakistan's Chief Justice Iftikhar Muhammad Chaudhry faced a judicial tribunal for a second time on Friday.
Hundreds of the judge's supporters chanted slogans like "justice lead, we will follow". Many also voiced their dislike of President Musharraf who suspended the judge last week.
It was not long before police fired teargas.
Hundreds of extra police were deployed on the streets of Islamabad and used concrete blocks and coils of barbed wire to seal off the city centre.
Dozens of people were arrested in Islamabad and across the country, despite overnight raids by police to detain opposition party activists and Muslim hardliners.
Demonstrators hurled rocks, bottles and tear gas shells at paramilitary troops and police outside the Supreme Court in several hours of violence.
Among those arrested by plain-clothes police was Qazi Hussain Ahmed, the president of Pakistan's main alliance of religious parties, the MMA.