It's the second such death at the hospital in less than a year.
The 50-year-old man was rushed to the emergency unit at Maisonneuve-Rosemont hospital, where his death was confirmed.
The patient had been hospitalized since Friday. There are reports he suffered from mental health problems but the hospital wouldn't confirm that information for privacy reasons.
Hospital spokesman Andre Bouthillier says support is being offered to the man's family.
A 74-year-old patient jumped in a similar incident at the hospital in October 2011.