About 50 demonstrators gathered in the downtown square across from the Montreal stock-exchange building where protesters set up their local camp a year ago. After occupying the square for about a month last fall, they were forcibly removed by police in November.
One year later, people were back to make brief speeches and several dozen then marched through downtown streets, chanting along the way.
The protesters, many of them wearing black and with their faces covered, disrupted traffic.
At one point, they tried to enter the downtown offices of Quebec's Caisse de depot pension-fund manager, but the doors were locked. They also entered the offices of engineering firm SNC-Lavalin, but they were chased out of the building.
A few minutes later, riot-equipped police rushed the small crowd as it made its way along Ste-Catherine street, one of the city's main downtown arteries. That's when the arrests were made.
A Montreal police spokesman says three people were charged under a municipal bylaw, with disturbing the peace, but were later released.
Meanwhile, in Toronto, about 50 people turned out for an Occupy rally to mark the anniversary there. Demonstrators with the movement met in Toronto's financial district and marched to St. James Park, where they planned to stay until about 11 p.m.
In an online listing for the event, organizers said they aim to celebrate the tent village where they "found each other and began to build a movement for change.''