The 2004 Eastern League season began on approximately April 1 and the regular season ended on approximately September 1.
The New Hampshire Fisher Cats defeated the Altoona Curve 3 games to 0 to win the Eastern League Championship Series.
- Green shade indicates that team advanced to the playoffs
- Bold indicates that team advanced to ELCS
- Italics indicates that team won ELCS
Statistical league leaders
The New Hampshire Fisher Cats defeated the Binghamton Mets in the Northern Division playoffs 3 games to 1.
The Altoona Curve defeated the Erie SeaWolves in the Southern Division playoffs 3 games to 0.
The New Hampshire Fisher Cats defeated the Altoona Curve in the ELCS 3 games to 0.