These determined the Eastern Canadian representative in the 1990 Allan Cup Final.
With Senior hockey on the demise, the Canadian Amateur Hockey Association awarded 2 Allan Cup berths to Manitoba’s Central Amateur Senior Hockey League.
Best of 7
- Montreal 9 Thunder Bay 2
- Thunder Bay 7 Montreal 4
- Montreal 6 Thunder Bay 2
- Thunder Bay 6 Montreal 3
- game 5, 7, or 7 unknown
Montreal Chomedy beat Thunder Bay Twins.
Montreal Chomedy advanced to the 1990 Allan Cup Final.
List of Eastern Canada Allan Cup Playoffs