The 2003–04 New Jersey Nets season was the Nets' 37th season in the National Basketball Association, and 28th season in East Rutherford, New Jersey. After speculating that he would sign with the defending champion San Antonio Spurs in the off-season, Jason Kidd signed a 6-year, $99 million deal to stay with the Nets.
The team acquired All-Star center and two-time Defensive Player of the Year Alonzo Mourning, who missed all of last season due to his worsening kidney condition. However, after just twelve games, Mourning retired on November 25, 2003, due to complications from his kidney disease.
After a 22–20 start to the season, Byron Scott was fired as head coach and was replaced with Lawrence Frank, as the Nets went on a 14-game winning streak at midseason. With Frank as interim head coach, the Nets overcame adversity, ending the season with a 47–35 record. Despite this, the Nets still managed to repeat as Division Champions and earn the number 2 spot in the Eastern Conference.
After sweeping the New York Knicks in the opening round of the playoffs, the second round pitted the Nets against the Detroit Pistons in last year's Conference championship rematch. However, Detroit would get revenge this time, and would eventually win the series in seven games, ending the 2003–04 season for the Nets. The Pistons would go on to defeat the Los Angeles Lakers in the 2004 NBA Finals to win their third NBA championship.
Following the season, Kenyon Martin was traded to the Denver Nuggets, Kerry Kittles was traded to the Los Angeles Clippers, and Rodney Rogers signed as a free agent with the New Orleans Hornets. Martin and Kidd both represented the Eastern Conference at the 2004 NBA All-Star Game, which was held in Los Angeles. This was Kenyon Martin's only All-Star game appearance.
Offseason
Draft picks
Roster
Roster notes
Center Alonzo Mourning retired on November 25.
Regular season
Season standings
z – clinched division title
y – clinched division title
x – clinched playoff spot
Record vs. opponents
Game log
Playoffs
|- align="center" bgcolor="#ccffcc" | 1 | April 17 | New York | W 107–83 | Richard Jefferson (21) | Kenyon Martin (12) | Jason Kidd (13) | Continental Airlines Arena18,206 | 1–0 |- align="center" bgcolor="#ccffcc" | 2 | April 20 | New York | W 99–81 | Kenyon Martin (22) | Kenyon Martin (16) | Jason Kidd (8) | Continental Airlines Arena19,918 | 2–0 |- align="center" bgcolor="#ccffcc" | 3 | April 22 | @ New York | W 81–78 | Martin, Kidd (19) | Kenyon Martin (15) | Richard Jefferson (10) | Madison Square Garden19,763 | 3–0 |- align="center" bgcolor="#ccffcc" | 4 | April 25 | @ New York | W 100–94 | Kenyon Martin (36) | Kenyon Martin (13) | Jason Kidd (7) | Madison Square Garden19,763 | 4–0 |-
|- align="center" bgcolor="#ffcccc" | 1 | May 3 | @ Detroit | L 56–78 | Kerry Kittles (15) | Jason Kidd (7) | Jason Kidd (6) | The Palace of Auburn Hills22,076 | 0–1 |- align="center" bgcolor="#ffcccc" | 2 | May 7 | @ Detroit | L 80–95 | Jefferson, Martin (19) | Jason Collins (10) | Jason Kidd (11) | The Palace of Auburn Hills22,076 | 0–2 |- align="center" bgcolor="#ccffcc" | 3 | May 9 | Detroit | W 82–64 | Richard Jefferson (30) | Kenyon Martin (9) | Jason Kidd (12) | Continental Airlines Arena19,000 | 1–2 |- align="center" bgcolor="#ccffcc" | 4 | May 11 | Detroit | W 94–79 | Jason Kidd (22) | Kenyon Martin (15) | Jason Kidd (11) | Continental Airlines Arena19,860 | 2–2 |- align="center" bgcolor="#ccffcc" | 5 | May 14 | @ Detroit | W 127–120 (3OT) | Richard Jefferson (31) | Jefferson, Kittles (11) | Jason Kidd (8) | The Palace of Auburn Hills22,076 | 3–2 |- align="center" bgcolor="#ffcccc" | 6 | May 16 | Detroit | L 75–81 | Richard Jefferson (23) | Jefferson, Martin (7) | Jason Kidd (8) | Continental Airlines Arena19,968 | 3–3 |- align="center" bgcolor="#ffcccc" | 7 | May 20 | @ Detroit | L 69–90 | Kerry Kittles (18) | Kenyon Martin (12) | Jason Kidd (7) | The Palace of Auburn Hills22,076 | 3–4 |-