Support workers at UQAM used the first day of the fall session Tuesday to stage a noisy, 24-hour protest.
Classes were not cancelled, but some services were affected; the university's cafeteria and sports centre remained closed for the day.
Support workers have been without a collective contract for two years now.
The main sticking point stalling negotiations is salary.
"The money on offer is not enough," said union president Louisa Cordeiro. "It's not fair. We work very hard. We have students at heart, the university too, but we deserve better because we are in the middle of university activities."
Full university services resume Wednesday.