"Tina was committed to doing the monologue with Lindsay but both of her children got sick," Fey's rep tells The New York Daily News. "She was unable to participate as planned."
Fey had cast Lohan as the lead in her 2004 comedy Mean Girls, which was received well by critics and audiences alike.
The March 3 edition of SNL was part of Lohan's attempt at a comeback. Although Fey couldn't make it, friends Jon Hamm and Jimmy Fallon made cameos. It was the second-highest rated episode of the show this season after Charles Barkley's hosting gig.