The 1904–05 Manitoba Hockey Association (MHA) season was won by the Rat Portage Thistles. After the season the Thistles challenged Ottawa for the Stanley Cup, but lost in a three-game series.
Tom Phillips returned to the Thistles after attending McGill University and a year in Toronto. Phillips brought along goaltender Eddie Giroux, with whom he had played with in the 1903–04 season for the Toronto Marlboros.
| Team | Games Played | Wins | Losses | Ties | Points | |
|---|---|---|---|---|---|---|
| Rat Portage Thistles | 8 | 7 | 1 | 0 | 14 | |
| Winnipeg Rowing Club | 10 | 6 | 3 | 1 | 12 | |
| Portage la Prairie Bisons | 10 | 4 | 5 | 1 | 9 | |
| Brandon Wheat City | 10 | 4 | 6 | 0 | 8 | |
| Winnipeg Victorias | 10 | 2 | 8 | 0 | 2 |
After the season, the Thistles challenged the Ottawa Hockey Club in Ottawa
In March 1905, the Rat Portage Thistles issued another challenge to the Senators. The Ottawa star Frank McGee did not play in the first game and the Thistles crushed Ottawa, 9–3. However, he returned to lead the Senators to 4–2 and 5–4 victories in games two and three, respectively. McGee scored the winning goal in the third game.
| Date | Winning Team | Score | Losing Team | Location | |
|---|---|---|---|---|---|
| March 7, 1905 | Rat Portage Thistles | 9–3 | Ottawa Senators | Dey's Arena | |
| March 9, 1905 | Ottawa Senators | 4–2 | Rat Portage Thistles | ||
| March 11, 1905 | Ottawa Senators | 5–4 | Rat Portage Thistles | ||
| Ottawa wins best-of-three series 2 games to 1 | |||||