The 1975 Hewitt-Dudley Memorial Trophy was a series of playoff rounds to determine the Eastern Canada seed in the 1975 Centennial Cup.
Teams
- CJHL - Smiths Falls Bears
- IJHL - Charlottetown Colonels
- NBJHL - Cap Pele Fishermen
- NJAHL - Gander Jr. Flyers
- OPJHL - Toronto Nationals
- QJAHL - St. Jerome Alouettes
- SOJAHL - Guelph CMC's
- TBJHL - Thunder Bay Case Eagles
Playdowns
Maritime Playdowns
- Charlottetown Colonels defeated Cap Pele Fishermen 3-games-to-none
- Charlottetown 5 - Cap Pele 4
- Charlottetown 4 - Cap Pele 1
- Charlottetown 6 - Cap Pele 4
- Gander Flyers defeated Charlottetown Colonels 3-games-to-none
- Gander 6 - Charlottetown 5
- Gander 6 - Charlottetown 4
- Gander 5 - Charlottetown 2
Quarter-final
- Guelph CMC's defeated Toronto Nationals 4-games-to-2
- Toronto 9 - Guelph 7
- Guelph 9 - Toronto 6
- Guelph 4 - Toronto 3
- Guelph 5 - Toronto 4
- Toronto 8 - Guelph 7
- Guelph 5 - Toronto 0
- Smiths Falls Bears defeated Gander Flyers 4-games-to-none
- Smiths Falls 5 - Gander 3
- Smiths Falls 8 - Gander 3
- Smiths Falls 6 - Gander 4
- Smiths Falls 8 - Gander 1
Semi-final
- Guelph CMC's defeated Thunder Bay Case Eagles 4-games-to-1
- Guelph 5 - Thunder Bay 3
- Thunder Bay 7 - Guelph 3
- Guelph 6 - Thunder Bay 2
- Guelph 12 - Thunder Bay 4
- Guelph 8 - Thunder Bay 4
- Smiths Falls Bears defeated St. Jerome Alouettes 4-games-to-1
- Smiths Falls 5 - St. Jerome 0
- Smiths Falls 4 - St. Jerome 2
- Smiths Falls 5 - St. Jerome 1
- St. Jerome - Smiths Falls
- Smiths Falls 8 - St. Jerome 4
Final
- Guelph CMC's defeated Smiths Falls Bears 4-games-to-2
- Guelph 8 - Smiths Falls 3
- Smiths Falls 4 - Guelph 3
- Guelph 7 - Smiths Falls 2
- Guelph 6 - Smiths Falls 4
- Smiths Falls 6 - Guelph 3
- Guelph 5 - Smiths Falls 2