NFL commissioner Paul Tagliabue will retire in July after more than 16
years in charge of the league.
Tagliabue, 65, succeeded Pete Rozelle in 1989 and last year signed a two-year contract extension to complete the NFL's TV and labour deals.
The TV contract was negotiated in April 2005 and a labour deal was agreed after tough negotiations earlier this month.
Tagliabue said: "I believe that now is a positive time to make the transition to a new commissioner."
Roger Goodell, the NFL's chief operating officer, and Atlanta Falcons general manager Rich McKay are the two leading candidates to succeed him.
Baltimore Ravens president Dick Cass is considered to have an outside chance.
Tagliabue's term will be remembered most for stability following strikes in 1982 and 1987.
His close relationship with Gene Upshaw, the players' union executive director, finally led to a long-term agreement after five years without a contract.
He also oversaw a massive stadium-building programme.
More than two-thirds of the NFL's 32 teams are either playing in or building stadia that didn't exist when he took over as the league's chief.
Before becoming commissioner, Tagliabue was a league lawyer who spent much of that time as the NFL's representative and unofficial lobbyist in Washington.