Pennsylvania State University (Penn State) football coach Joe Paterno and university president Graham Spanier were fired over their handling of a sex abuse scandal, the US university's board of trustees has said.
Paterno said on Wednesday that he would retire at the end of the season, but a statement from the trustees later said
his dismissal was effective immediately.
John Surma, vice-chairman of the board, said it was "in the best interest of the university that a change of leadership to deal with the difficult issues we are facing" take place.
Paterno, who has not been implicated in the case, has been accused of failing to act over alleged child abuse by longtime assistant coach Jerry Sandusky.
The 84-year-old was in his 46th year as head coach of the Nittany Lions, Penn State's football team.
He said he was "absolutely devastated" by the Sandusky allegations, who is charged with molesting eight boys between 1994 and 2009. Sandusky has said he is innocent.
"This is a tragedy," Paterno said in a statement. "It is one of the great sorrows of my life. With the benefit of hindsight, I wish I had done more."
Hundreds of students demonstrated in support of Paterno on Wednesday. Police in riot gear used pepper spray to control the crowd.
"It's criminal the way he went out," senior offensive tackle Chima Okoli said, "because he's done so much for this university and he's had such a legacy. This isn't a fitting end for all the work he's done, not only for Penn State but for the world."
The university is reeling over the allegations targeting Sandusky, who allegedly attacked youths at his house, in the football team's locker room showers and on team road trips.
Two school administrators stepped down over the weekend and have been charged with failing to notify authorities of suspected abuse and with perjury.They too have denied wrong-doing.
Paterno has been strongly criticised for failing to take more action when suspicions about Sandusky were brought to his attention in 2002.
At that time, a young assistant coach said he saw Sandusky raping a boy, who the witness thought was about 10 years old, in the Penn State team's showers.
He reported the incident to Paterno, who told a superior.
Paterno has noted that Sandusky had retired by then, although he still had an office on campus, and said the witness did not tell him the graphic nature of the alleged assault.