The two men, believed to be in their 20s, were stabbed during a fight outside a residence at 136 Rainbow Cres. in the Erin Mills Parkway and Burnhamthorpe Road area.
The incident happened around 1:30 this morning.
Forensic officers went to the scene to gather evidence. The homicide unit was also called to investigate.
Const. George Tudos said police are urging any witnesses to the stabbing to come forward with any details of the attack.
"There was a large gathering, so there was quite a number of people situated within one of the residences," he said.