<P> "Didn't We Almost Have It All?" is the third season finale and the 61st overall episode from the medical drama series, Grey's Anatomy . The episode runs for 53: 05 minutes, making it the longest episode of the series, excluding two - part episodes . </P> <P> The episode marked Isaiah Washington (Dr. Preston Burke)'s final appearance to the series until Season 10, Episode 22 entitled' We Are Never Ever Getting Back Together' . It was Kate Walsh (Addison Montgomery)'s last episode with regular billing who became a main character in Grey's Anatomy's spin - off Private Practice and Chyler Leigh (Dr. Lexie Grey)'s last appearance with recurring billing as she would be upgraded to a series regular in season four . Loretta Devine (Adele Webber), Diahann Carroll (Jane Burke), Tsai Chin (Yang's mother), Elizabeth Reaser (Rebecca Pope), Steven W. Bailey (Joe), Jack Yang (Walter) all reprised their role as guest stars . </P> <P> The episode opens to a voice - over narrative from Richard Webber (James Pickens, Jr .). Addison gets to the ER with the woman from the bar, the previous episode . Burke starts treating her and decides that the babies must be born . Joe and Walter adopt them . Derek, Mark and Bailey start treating the climber . The other climbers eventually talk to the police . Cristina tries to write her vows . Callie writes them on Cristina's hand . At work, Cristina discovers that the wedding has given her the day off . Jeff Pope arrives and hugs Rebecca . Alex asks Jeff why he didn't search for his wife before . Rebecca wants Alex, but he tells her to stay with her' decent guy' . Derek tells Meredith that he met a girl in the bar . Meredith seems confused . Meanwhile, Adele has a miscarriage, revealing Richard was the father . Mama Burke forces Cristina to remove her eyebrows; she panics and convinces Bailey to let her scrub in . Bailey agrees, having found out that Callie is the new chief resident . Derek removes the axe from the fourth climber while Burke treats the new babies . Callie and George agree to have children, but Izzie tells George she's in love with him . The interns receive their test results . George hides the fact that he didn't pass . Derek feels Meredith is taking him for granted . She evades responding and goes to the chapel . Mark, Addison and Burke are rejected as Chief candidates . At the chapel, Burke finds out Derek is not the new Chief, though Derek doesn't explain . Addison tells Alex to fight for Rebecca . Outside SGH, Bailey and George talk . She thinks that she failed him, but he says: "I failed you". Alex decides to find Rebecca . Callie tells Izzie she is planning to have a baby; Izzie is stunned . Cristina realizes that she washed her vows off when she scrubbed in, and freaks out . Meredith convinces her to go on . Burke sees the delay and calls off the wedding, feeling he has forced her to change . He walks away . Meredith tells everybody that it is over . She looks at Derek, and leaves the Chapel . Cristina arrives at Burke's apartment . He's gone . Cristina starts shaking uncontrolablly and crying . To calm her down, Meredith squeezes and hugs her . George runs into the new interns, and meets Lexie Grey, Meredith's half sister . Richard tells Derek he is the new Chief, but Derek suggests he start over . We see the Chief looking over the Hospital . </P> <P> After an off - screen incident, in which Isaiah Washington aimed a homophobic slur at gay actor T.R. Knight, ABC chose not to renew Washington's contract, making "Didn't We Almost Have It All?" his final appearance to the series . It was also the last episode to feature Chyler Leigh as a guest star, since she was promoted to star billing in the season four premiere and Kate Walsh's last regular episode as she would only make guest appearances in the future, due to her being a main character on the Grey's Anatomy spin - off Private Practice . </P>

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