The incident happened around 8 p.m. on Wednesday on De La Vigne Street on Nuns' Island.
Police say a 55-year-old man walking down the street was attacked by someone with a sharp object.
"The man suffered some injuries in his lower back. The man was transferred to the hospital where we don't fear for his life," said Const. Daniel Lacoursière of the Montreal police.
Radio-Canada is reporting that the victim was Dr. AlainSirard, from the hospital’s socio-legal clinic.
He made the news last week when Radio-Canada’s Enquête and CBC News reported that some parents said he had unjustifiably reported them to youth protection services.
Ste-Justine Hospital officials issued a statement confirming that one of its doctors had been attacked.
In the release, it said it condemns all forms of physical and psychological violence against members of its institution.
Police would not confirm the victim's identity or comment on the motivation for the attack.
Montreal police said that they don't have any leads on a suspect at the moment.
"He wasn't seen by the victim and he left the scene," said Lacoursière.