The 1998–99 NBA season was the 53rd season of the National Basketball Association (NBA). Due to a lockout, the season did not start until February 5, 1999, after a new six-year Collective Bargaining Agreement was reached between the NBA and the National Basketball Players Association. All 29 teams played a shortened 50-game-per-team regular season schedule and the 16 teams who qualified for the playoffs played a full post-season schedule. That season's All-Star Game, which would have been held in Philadelphia, was also canceled. The season ended with the San Antonio Spurs winning the franchise's first NBA championship, beating the New York Knicks 4 games to 1 in the 1999 NBA Finals. This was the 50th season since the BAA and NBL had merged into the NBA.
The third lockout in the history of the NBA lasted from July 1, 1998, to January 20, 1999. NBA owners were seeking changes to the league's salary cap system and a ceiling on individual player salaries. The National Basketball Players Association opposed the owners' plans and wanted raises for players who earned the league's minimum salary.
As the labor dispute continued into September, the preseason was shortened to just two games instead of the normal eight, and training camps were postponed indefinitely. By October, it became the first time in NBA history that games were canceled due to a labor dispute. Further games were canceled by November and December, including the league's Christmas games (which had been played on an annual basis since 1947) and All-Star Game, which had been scheduled to be played on February 14, 1999. The preseason consisted of 2 exhibition games.
An agreement between the owners and players was eventually reached on January 18, 1999. When play resumed, the regular season was shortened to 50 games per team, as opposed to the normal 82. To preserve games between teams in the same conference, much of the time missed was made up for by skipping well over half of the games played between teams in the opposite conference. As a result, some teams did not meet each other at all during the course of the shortened season.
Michael Jordan announced his retirement for the second time on January 13, 1999, while the lockout was still ongoing. He would later return to play two more seasons for the Washington Wizards from 2001–2003.
The San Antonio Spurs became the first former ABA team to win a championship. (They are one of two surviving ABA teams to win an NBA Title, as the Nuggets won a title in 2023. The Nets and Pacers have not yet won the NBA Championship despite both appearing in at least one NBA Finals.)
The Clippers tied the 1988–89 Miami Heat for the longest losing streak to start the season (17) from February 5 until March 11 when they defeated the Sacramento Kings. In December 2009, this record was broken by the New Jersey Nets who lost the first eighteen games of the season.
For the first time in 15 seasons, the Chicago Bulls missed the playoffs. They would also become the second defending champion in NBA history that failed to make the playoffs, joining the 1969–70 Boston Celtics.
Teams in bold advanced to the next round. The numbers to the left of each team indicate the team's seeding in its conference, and the numbers to the right indicate the number of games the team won in that round. The division champions are marked by an asterisk. Home court advantage does not necessarily belong to the higher-seeded team, but instead the team with the better regular season record; teams enjoying the home advantage are shown in italics.