About 200 demonstrators - mainly women's rights groups but also anti-corporate protesters - have marched against Montreal's biggest annual tourist draw, Formula One's Grand Prix.
Marchers hit the streets behind a huge banner slamming the prostitution they see as a parallel "Formula One of Sex Exploitation," as their banner read, stopping near several hotels where they said prostitution was common.
"In my opinion, prostitution is still a paid rape," Laurence Fortin, a graduate student and sociology researcher, told AFP.
There were no immediate reports of any violence. Riot police were out on guard on a pedestrian street with Formula One stands set up on it.
On Friday, lines of police officers also blocked all access to the stands of the Grand Prix, which many student protesters consider an "elitist event."
Protesters this week also have demonstrated against a special law passed by the Quebec government restricting the right to protest.
Special Law 78 requires organizers to give police at least eight hours advance warning of times and locations of protest marches, with hefty fines imposed for failing to do so.
The measure was passed on May 18 in an effort to quell the demonstrations sparked by a plan to increase university tuition, but so far it has only served to galvanize opposition to the government.
Students have rejected a government offer to reduce the tuition hike by Can$35 ($44) per year, which would bring the total increase to Can$1,533 over seven years instead of Can$1,778.
Student leaders vowed to target the Grand Prix when talks in Quebec broke down last week after students rejected a government offer to reduce the planned tuition hike.
Since February, hundreds of protesters have been arrested and clashes have erupted sporadically as more than 165,000 students have refused to attend class and tens of thousands have taken part in nightly demonstrations.