The 1904 Canadian Amateur Hockey League (CAHL) season was the sixth season of the league. Teams played an eight-game schedule. This was a tumultuous year as Ottawa resigned in February and defaulted four games. The Quebec Hockey Club placed first to take the championship. Quebec did not play for the Stanley Cup.
Also, prior to the start of the season a rival hockey league, the Federal Amateur Hockey League was started, with the Montreal Wanderers taking most of the 'Little Men of Iron' from the Montreal Hockey Club.
As the Wanderers had signed players from Montreal, it was forbidden for teams to play games against FAHL teams, and for team officials to participate in FAHL activities.
This season saw several impressive rookies including Frank Patrick for Montreal Victorias, Ernie (Moose) Johnson for Montreal and Alf Smith and Jim McGee for Ottawa.
The season started out with Ottawa winning their first four games. However, in their third game against the Victorias, the Ottawa team arrived 1½ hours late. The game was called at midnight, with Ottawa ahead 4–1. After a game where the Shamrocks arrived late in Ottawa, the League levied fines against the Shamrocks and Ottawa, and ordered the Ottawa-Victorias game to be replayed. Despite a threat from Mr. Dickson of Ottawa that Ottawa would resign if the game was to be replayed, the League continued to demand that the game be played. The Ottawa club offered to play it if it had a bearing on the league championship, but this was not acceptable to the league. In the end, Ottawa resigned from the league and the league considered the final four games to be forfeits. This overshadowed a great season from Quebec, which won the CAHL season with a record of 5–1 (plus two wins by forfeit).