Forty-five nurses work in the Lakeshore General Hospital, but they say they need almost twice that number in order to do their jobs properly.
They say the understaffing problem in the ER causes some patients to lack the attention they need.
They're are asking for at least 30 more nurses in the ER. Protesters said the hospital often fills positions with casual or temporary nurses who are not familiar with the hospital.
"We have a lot of people from agencies that come work with us. The problem is giving more workload to our members here because they have to show them things about the emergency," said Michel Léger, president of United Health Care Professionals.
Quebec's Federation of Nurses said the problem is directly related to poor management.
Lakeshore Hospital changed its board of directors in February.
The hospital's interim executive director, Henri Elbaz, said Friday's protests caught him off guard.
He said the hospital is trying to attract more permanent nurses and hopes to hire some in the coming months.