The Hollywood Reporter says Plimpton will play a multi-episode arc on the hit series as a young patient's mother. The sixth season of "Grey's Anatomy" kicks off Sept. 24.
Martha Plimpton received Tony nominations for her performances in Pal Joey, Top Girls and The Coast of Utopia. Her other Broadway credits include Shining City and Sixteen Wounded.
For more information visit http://abc.go.com/primetime/greysanatomy/index?pn=index.