Authorities say the 48-year-old American man fell off the lookout on the east side of the mountain at about 1 a.m. on Sunday.
The man's body was found at the base of a tree, about 100 metres from where he fell.
Members of the Montreal fire department's managed to reach him in about 20 minutes, but were unable to revive him.
Montreal police say it doesn't appear alcohol or foul play was involved.
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