The collective bargaining agreement (CBA) between the league and the Professional Lacrosse Players' Association expired before the 2004 season, and the lack of a new agreement caused a 12-day players strike in December 2003. On December 17, the NLL and PLPA announced that the previous CBA had been extended by one year, guaranteeing that the 2004 season would be played without strikes or lockouts.
2004 was a season of turmoil for the NLL – two franchises disappeared while three others moved cross-country, causing a division realignment. Gone was the three-division format that had been used in the preceding two seasons; the league was now split into East and West divisions. The Ottawa Rebel and New York Saints franchises both folded, and the following teams moved:
January 9: The Anaheim Storm play their first ever home game, losing to the Arizona Sting 19–18 in the first triple overtime game in NLL history. This is a record not likely to ever be broken – before the 2005 season, the NLL changed overtime periods to 15 minutes from five. Since then, no games have even seen double overtime.
x–Clinched playoff berth; c–Clinched playoff berth by crossing over to another division; y–Clinched division; z–Clinched best regular season record; GP–Games Played; W–Wins; L–Losses GB–Games back; PCT–Win percentage; Home–Record at Home; Road–Record on the Road; GF–Goals scored; GA–Goals allowed; Diff–Difference between goals scored and allowed