1989–90 Dallas Mavericks season

• John MacLeod (fired) (5–6)
• Richie Adubato (42–29) (lost to Trail Blazers 0–3)
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The 1989–90 Dallas Mavericks season was the tenth season for the Dallas Mavericks in the National Basketball Association. A year after missing the playoffs, the Mavericks received the eighth overall pick in the 1989 NBA draft, and selected power forward Randy White out of Louisiana Tech University, and later on fired head coach John MacLeod at the end of November, replacing with him Richie Adubato. However, things would not go smoothly at all for the Mavericks as Roy Tarpley found himself in hot water again, as he was arrested in November for driving under the influence of drugs.

The Mavericks played above .500 in winning percentage for the first half of the regular season, holding a 26–22 record at the All-Star break. As the season progressed, the team released Adrian Dantley to free agency; Dantley averaged 14.7 points per game in 45 games with the team. The Mavericks finished in third place in the Midwest Division with a 47–35 record, earned the sixth seed in the Western Conference, and returned to the NBA playoffs after a one-year absence.

Rolando Blackman led the team in scoring averaging 19.4 points per game, while Derek Harper averaged 18.0 points, 7.4 assists and 2.3 steals per game, and was named to the NBA All-Defensive Second Team, and Tarpley provided the team with 16.8 points, 13.1 rebounds and 1.6 blocks per game, despite only playing just 45 games. In addition, Sam Perkins contributed 15.9 points and 7.5 rebounds per game, and James Donaldson provided with 9.1 points and 8.6 rebounds per game. Off the bench, Herb Williams averaged 8.6 points, 4.8 rebounds and 1.3 blocks per game, while Brad Davis contributed 6.4 points and 3.3 assists per game, Bill Wennington provided with 4.5 points and 3.3 rebounds per game, and White averaged 4.3 points and 3.1 rebounds per game.

During the NBA All-Star weekend at the Miami Arena in Miami, Florida, Blackman was selected for the 1990 NBA All-Star Game, as a member of the Western Conference All-Star team; it was his final All-Star appearance. Harper finished tied in third place in Defensive Player of the Year voting, while Tarpley finished tied in sixth place in Most Improved Player voting.

In the Western Conference First Round of the 1990 NBA playoffs, the Mavericks faced off against the 3rd–seeded Portland Trail Blazers, who were led by the quartet of All-Star guard Clyde Drexler, Terry Porter, All-Star center Kevin Duckworth and Jerome Kersey. The Mavericks lost the first two games to the Trail Blazers on the road at the Memorial Coliseum, before losing Game 3 at home, 106–92 at the Reunion Arena, thus losing the series in a three-game sweep. The Trail Blazers would lose to the defending NBA champion Detroit Pistons in five games in the 1990 NBA Finals.

This season would also be the last time the Mavericks appeared in the NBA playoffs until the 2000–01 season, as what would follow was a ten-year playoff drought. Following the season, Perkins signed as a free agent with the Los Angeles Lakers after six seasons with the Mavericks.