He also played for the Philadelphia 76ers, the Atlanta Hawks, the Portland Trail Blazers, the Boston Celtics, the Minnesota Timberwolves, the Detroit Pistons, the San Antonio Spurs, the Charlotte Bobcats and the Los Angeles Lakers.

Following Slater and Breaux's graduations, Ratliff saw increased playing time his sophomore season, and would establish himself as Wyoming's starting center for his junior and senior year.

[10] In his first full season in Philadelphia, Ratliff posted 11.2 points, 8.1 rebounds and 3.0 blocks per game, while being named to the NBA All-Defensive Second Team.

[15][16] On February 22, Ratliff was traded to the Atlanta Hawks with Toni Kukoč, Nazr Mohammed, and Pepe Sánchez for Roshown McLeod and Dikembe Mutombo.

Though a fan favorite in Philadelphia and arguably a better fit for the team than Mutombo, Larry Brown decided to move forward with the trade once it was determined Ratliff would not be back in time for the playoffs.

Midway through the 2003–04 season, he was dealt to the Portland Trail Blazers, along with Shareef Abdur-Rahim and Dan Dickau, for Rasheed Wallace and Wesley Person.

[24] Ratliff missed games over the next two seasons dealing with nagging injuries, and eventually lost his starting job to Joel Przybilla.

In June 2006, the Boston Celtics acquired Ratliff along with Sebastian Telfair from the Portland Trail Blazers in exchange for the draft rights of Randy Foye, power forward–center Raef LaFrentz, and point guard Dan Dickau.

[25] In July 2007, he was traded along with Gerald Green, Ryan Gomes, Al Jefferson, Sebastian Telfair, and draft picks, to the Minnesota Timberwolves for Kevin Garnett.