The hospital drama ends after 15 seasons, but not without bringing back former cast members like George Clooney, Anthony Edwards, and Noah Wyle

By Lynette Rice
Updated March 06, 2009 at 05:00 AM EST

When George Clooney left ER in 1999, executive producer John Wells began to conceive the series finale of his NBC drama. Okay, maybe he was a tad premature, but he realized that it was quite possible that all of ER’s original cast members would eventually jump ship (as they did) and he wanted to be prepared. And he insists that his plans for the two-hour finale on April 2 at 9 p.m. (preceded by a one-hour retrospective) haven’t changed much over the past decade. ”I really wanted to say to the audience, ‘This place is still here and if you took the wrong off-ramp in Chicago, you’d end up in front of the hospital where these people have always worked,”’ says Wells, who penned the final episode, which is currently shooting.

Actually, the long goodbye to County General has been going on since November: Early cast members Noah Wyle (Dr. Carter), Laura Innes (Dr. Weaver), and Anthony Edwards (Dr. Greene) have already guest-starred. And Clooney — whose return as Dr. Doug Ross is one of the worst-kept secrets in TV — will be joined by costars Julianna Margulies (Nurse Hathaway) and Eriq La Salle (Dr. Benton) for much-anticipated cameo appearances throughout March sweeps. Wells won’t say exactly when we’ll see them (nor will NBC confirm reports that Clooney will appear March 12), but he does suggest that fans set their TiVos ASAP. ”You should not expect them all to be in the finale,” warns Wells. ”We’ve spread them out over the season. I didn’t want to do something like somebody dies, or there is a celebration, or the hospital closes, so that’s why everybody comes back. I wanted it to be natural.”