A quarrel between former lovers closed the Place-des-Arts metro station late Tuesday night.
According to police the first 9-1-1 call came in at about 10:15 P.M. after a woman was attacked by a man wielding a knife.
Witnesses told investigators they saw the two arguing before the man slashed her with the weapon.
The 39-year-old woman was taken to hospital where she was treated for superficial wounds to her upper body.
The suspect, a 37-year-old man, was arrested at the corner of Sherbrooke and Bleury over the course of the night.