Oklahoma football coach Bob Stoops announced his retirement Wednesday after 18 seasons at the school.

Stoops is expected to address the team Wednesday.

“After 18 years at the University of Oklahoma, I've decided to step down as the head football coach," Stoops said in a statement. "I understand there has been some speculation about my health. My health was not the deciding factor in this decision and I've had no incidents that would prevent me from coaching. I feel the timing is perfect to hand over the reins. The program is in tremendous shape. We have outstanding players and coaches and are poised to make another run at a Big 12 and national championship."

Stoops, 56, compiled a 190-48 record during his career which included one national championship and 10 Big 12 titles. He is the school's all-time winningest coach, passing both Barry Switzer and Bud Wilkinson, who each won three national titles during their careers in Norman.

Stoops was hired in 1999 after serving as defensive coordinator at Florida under Steve Spurrier. He was previously an assistant at Kansas State with Bill Snyder and at his alma mater Iowa working for college coach Hayden Fry

Oklahoma had won just 12 games in three seasons with John Blake as coach before Stoops arrived. The Sooners went 7-5 in his first season and played in the Independence Bowl. That success set the stage for a 13-0 run to a national championship in 2000 that culminated in a 12-0 defeat of Florida State in the Orange Bowl.

Stoops would lead his team to three more BCS title games, losing to LSU, Southern California and Florida. That last of those losses was in 2008. The Sooners made the College Football Playoff in 2015 and fell to Clemson in the semifinals.

The list of Stoops' accomplishments includes coaching Heisman Trophy winners Jason White and Sam Bradford and several All-Americans, notably Roy Williams, Adrian Peterson, Trent Williams and Gerald McCoy.

He won more games in his first 18 seasons than any other college coach. Among the successes was an 11-7 record against rival Texas and a 14-4 mark against Oklahoma State.

The Sooners were particularly difficult to beat in Norman. Stoops was 101-9 at Gaylord Memorial Stadium, including a school-record 39-game home winning streak.

His departure creates some uncertainty for one of the nation's top programs that was again expected to contend for a national championship this season.

Offensive coordinator Lincoln Riley is expected to replace Stoops. Riley interviewed with Houston last winter and recently signed an extension with the school. He, like Stoops and Switzer, will assume the job having only served as a coordinator.

While that model work in both occasions, it did not work for two of Switzer's successors - Gary Gibbs and Blake - before Stoops arrived.