The 2003 National Lacrosse League season is the 17th season in the NLL that began on December 27, 2002, and concluded with the championship game on May 3, 2003.

In 2003, the NLL became the first major men's sports league in North America to feature a woman playing in a regular-season game. Ginny Capicchioni, a stand-out goaltender at Sacred Heart University, was signed by the New Jersey Storm as their third-string goaltender. She dressed for three games, though only played in one. Capicchioni collected one loose ball and made six saves while allowing 7 goals in 11 minutes of play.^[1]

2003 saw the Montreal Express suspend operations, and also saw the Washington Power move to Colorado, where even they were unprepared for the warm welcome they received in Denver. The franchise had drawn small crowds in Washington as well as in Pittsburgh and Baltimore before that, but averaged more than 16,000 fans per game^[2] in 2003, second in the league only to Toronto.

• January 31: John Tavares became the 3rd player in NLL history (after Gary and Paul Gait) with 400 career goals, scoring 5 and adding 6 assists as the Buffalo Bandits defeated the Columbus Landsharks 19–16^[3]

No NLL All-Star game was held in 2003.

Bold numbers indicate new single-season records. Italics indicate tied single-season records.

• 2003 in sports