thumb|The Memorial Cup trophy|alt=Silver bowl trophy with two large handles, mounted on a wide black plinth engraved with team names on silver plates.
The 2004 Memorial Cup (branded as the 2004 Mastercard Memorial Cup for sponsorship reasons) occurred May 15–23 at Prospera Place in Kelowna, British Columbia. It was the 86th annual Memorial Cup competition and determined the major junior ice hockey champion of the Canadian Hockey League (CHL). It featured the host team, the Kelowna Rockets as well as the winners of the Ontario Hockey League, Quebec Major Junior Hockey League and the Western Hockey League which were the Guelph Storm, Gatineau Olympiques and the Medicine Hat Tigers respectively.