2003 League of Ireland First Division

The 2003 League of Ireland First Division season was the 19th season of the League of Ireland First Division and the first to be played as a summer league.

Overview
The First Division was contested by 12 teams and Dublin City won the division. Each team played the other teams three times, totaling 33 games.

Promotion/relegation play-off
Four teams entered the promotion/relegation play-off. The second, third and fourth placed teams from the First Division were joined by the ninth placed team from the 2003 League of Ireland Premier Division.

Semi-final

 * 1st Legs


 * 2nd Legs

Derry City win 4–0 on aggregate

Finn Harps win 3–1 on aggregate

Final
Derry City win 2–1 on aggregate and retain their place in the Premier Division.