Police fired tear gas late Monday to disperse demonstrators who lit fires in the street of Sao Paulo to protest the looming impeachment of suspended president Dilma Rousseff.
Riot police and trucks dispersed several thousand protesters on the main Paulista avenue in the center of the country's economic capital.
The protest came as Rousseff defended herself in the capital Brasilia in the Senate, whose members were expected to vote to impeach her by Wednesday.
Protesters in Sao Paulo blocked streets with burning bins and barriers.
Some 2,000 Rousseff supporters also rallied near the Senate in Brasilia and a few hundred in Rio de Janeiro, but no incidents were reported.
"Temer out! Dilma come back," protesters in Brasilia yelled.
Nearby, a smaller group of a few dozen pro-impeachment demonstrators gathered at another point near the Senate, kept apart by police from the Rousseff supporters.
Rousseff was mounting an emotional last bid to avoid being removed from power for good, ending 13 years of leftist rule in Brazil.
Her rivals accuse her of fiddling the state accounts and blame her for a deep recession in Latin America's biggest economy.
Rousseff brands the impeachment drive a "coup."