ADDISON RETURNS TO SEATTLE GRACE TO PERFORM A GROUNDBREAKING SURGERY AND IS STRUCK BY THE CHANGES AMONG HER OLD FRIENDS, ON ABC'S "GREY'S ANATOMY"

Kate Walsh ("Private Practice") Guest Stars

Elizabeth Reaser Returns as Rebecca/Ava

"Piece of My Heart" � Addison returns to Seattle Grace to perform an operation and is taken aback by all of the changes in her old co-workers' lives. Meanwhile Meredith and Derek's clinical trial has its first patient, and Rebecca/Ava returns with shocking news for Alex, on "Grey's Anatomy," THURSDAY, MARCH 5 (9:00-10:02 p.m., ET) on the ABC Television Network. (Rebroadcast. OAD 5/1/08)

"Grey's Anatomy" stars Ellen Pompeo as Meredith Grey, Patrick Dempsey as Derek Shepherd, Sandra Oh as Cristina Yang, Katherine Heigl as Isobel "Izzie" Stevens, Justin Chambers as Alex Karev, T.R. Knight as George O'Malley, Chandra Wilson as Miranda Bailey, James Pickens, Jr. as Richard Webber, Sara Ramirez as Callie Torres, Eric Dane as Mark Sloan, Chyler Leigh as Lexie Grey and Brooke Smith as Erica Hahn.

Guest starring are Kate Walsh as Addison, Amy Madigan as Dr. Wyatt, Elizabeth Reaser as Rebecca, Clea Duvall as Jennifer, Lauren Stamile as Rose, Kathleen Rose Perkins as Sarah, Ken Barnett as Freddie, with Jason O'Mara as Phillip.

"Piece of My Heart" was written by Stacy McKee and directed by Mark Tinker.

"Grey's Anatomy" is broadcast in 720 Progressive (720P), ABC's selected HDTV format, with 5.1-channel surround sound and Spanish audio via SAP. This program carries a TV-14 parental guideline.

This episode of "Grey's Anatomy" will be available on ABC.com the day after airing on the network for users to watch online.