It's Oscar tradition for the previous year's victor of the Best Actor award to present the following year's award for Best Actress, but that won't be happening this year.
It is believed that Affleck - who won best actor a year ago for Manchester By The Sea - dropped out of presenting to keep the spotlight off the sexual harassment allegations made against him.
As women dominate on Oscar starring roles, the #metoo and Time's Up movement is also taking centre stage in the fallout of sexual harassment allegations which started with Harvey Weinstein and captured numerous big names.
Affleck, whose brother is fellow actor Ben, settled out of court with both women but maintains his innocence.
Last year, TIME reported that one of Affleck's accusers claims that he hopped into bed with her while she was sleeping while the other alleges that the Oscar victor tried to pressure her into staying in a hotel room and after she refused he "violently grabbed [her] arm in an effort to intimidate her into staying".
Comedian Jimmy Kimmel is hosting the ceremony at LA's Doby Theatre.