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ABC News' Thea Trachtenberg and Lauren Sher:

Long before shows like " Grey's Anatomy" "House" and "ER," there was "St. Elsewhere." Thirty years ago, the show was the first medical drama of its kind, and devoted fans followed the lives and loves inside the dingy South Boston teaching hospital for six seasons.

"More people died there than at any hospital, I think, in the history of television," joked Ed Begley Jr., who played Dr. Victor Ehrlich on the critically acclaimed but ratings-challenged show.

The "first hospital show, even the stars of our show had a tendency to die off and get killed," said comedian Howie Mandel, who played Dr. Wayne Fiscus. "We couldn't even save ourselves, let alone patients."

The fictional St. Eligious hospital, where the show took place, was staffed with a slew of now familiar faces, from actor Ed Begley Jr., to comedian Howie Mandel, "NCIS" star Mark Harmon and David Morse of "The Green Mile" and more. Even a young and relatively unknown Denzel Washington was part of the large, ever-changing ensemble cast.

"To this day, [Denzel] will call me from the set and go, 'Howie, how would you play this scene?'" the comedian Howie Mandel joked about this relationship with his castmate turned A-List movie star today. "I'm always there for him."

"Good Morning America" reunited with 12 members of the show's cast while they were gathered for a photo shoot for Entertainment Weekly magazine's Reunions Issue.

ABC News correspondent John Quinones talked with William Daniels (Dr. Mark Craig), Norman Lloyd (Dr. Daniel Auschlander), Christina Pickles (Nurse Helen Rosenthal), Mark Harmon (Dr. Robert Caldwell), Cynthia Sikes (Dr. Annie Cavanero), Ed Begley Jr. (Dr. Victor Ehrlich), David Morse (Dr. Jack Morrison), Howie Mandel (Dr. Wayne Fiscus), Eric Laneuville (Luther Hawkins), Stephen Furst (Dr. Elliot Axelrod), Bonnie Bartlett (Ellen Craig) and Chad Allen (Tommy Westphall) last month.

Although Denzel Washington couldn't make it, the rest of the cast shared some of their favorite memories from behind the scenes. Stand-up comic Howie Mandel was the class clown.

"He would always play practical jokes on me," said Stephen Furst who played Dr. Elliot Axelrod. "I was the heavy set guy there on the show and he scored my director's chair so when I sat down, it busted. …. I went on vacation one time, and I came home and there was a for sale sign in front of my house. He had listed my house with Century 21 while I was away."

William Daniels, the surly and self-centered heart surgeon Dr. Mark Craig, starred alongside his TV wife, Ellen Craig, who was played by his real-life wife Bonnie Bartlett on the show. Was working together all it's cracked up to be?

"It was wonderful. We love to work together right, Bill?" Bartlett said, poking fun at her real-life husband of 61 years.

"Give me a second will you?" Daniels joked.

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During the show's run from 1982 to 1988, the cast said fans would come up to them on the streets, and ask for everything from autographs to medical advice.

"I would find I was giving, dispensing advice some of the time. And actually, I wasn't far off a lot of the time," said Cynthia Sikes Yorkin, who played Dr. Annie Cavanero. "We got quite an education - what the diseases were and what … to look for, you know?"

Christina Pickles, who starred as nurse Helen Rosenthal, said she even gave a speech at the opening of a hospital in the Midwest during the show's run.

Mandel said that doctors at the hospital where his wife was giving birth were such fans of the show, they kept coming in and unnecessarily checking in on them during the delivery.

"It was embarrassing, because we were in a hospital here in the midst of 'St. Elsewhere' and the doctor came into the room that wasn't our doctor when my wife was in labor and I guess he just wanted to meet people because they loved the show and it represented him," Mandel said. "He didn't want to say that he was just a fan, so he checked how much my wife was dilating."

The show's fan following was in part because of the beloved cast but also because of the intense storylines. "'St. Elsewhere' was a show that brought a sense of truth, if you will forgive that suspicious word, to television, that had not been seen before on television," said star Norman Lloyd. "The star of the show was the writing." The writers never shied away from controversy. Main characters were written off in shocking ways: from Peter White getting shot in season 3, to Mark Harmon's popular character, the handsome plastic surgeon Dr. Bobby Caldwell, who contracted HIV.

"Originally, it was ALS, it was not AIDS and then they changed it," Harmon said.

Before "St. Elsewhere," the actors said it was unprecedented for a leading character to contract HIV/AIDS on TV.

"That was groundbreaking television. It doesn't seem like it now, but that was incredibly controversial in the subject matter and unheard of for a lead starring character in a series," Mandel said. "He contracted HIV, one of the other regulars was found out to be a rapist."

Dealing with such groundbreaking storylines, the group said the show was a launching pad and an "extraordinary" moment in their careers.

"I would say [the show was] maybe one of the most extraordinary things to happen in some of our careers," said David Morse. "It was a show that changed television in a lot of ways, and to be a part of something like that was certainly extraordinary."

In everyone's hearts at the interview was beloved executive producer Bruce Paltrow (yes, Gwyneth's father), who died in 2002. Actor-turned-director Eric Laneuville credits Paltrow for his foray into directing. "I started directing in the second season, and Bruce Paltrow was the reason for that," Laneuville said.

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Paltrow was one of the leaders on the set, but "NCIS" star Mark Harmon, who was starting out at the time, said the "St. Elsewhere" set had "teachers in every direction."

"I just always thought it was just an opportunity I so appreciated. I thought I earned it, but I was real thankful to be included in this group," Harmon said.

Today the show is best remembered for two things: its infinitely hummable theme song and having one of the most controversial finales of all time. The last few minutes suggest the entire series had been the musings of an autistic boy, seen staring at a snow globe.

"I think it was sort of left to the audience to sort of assume, but I know that some people felt betrayed that the characters weren't real and there's a certain amount of controversy over that," said Chad Allen, who played that little boy, Tommy Westphall.

"Can I just say that this interview is not actually happening," Mandel said. "It's all happening in Chad's head."

For more information on the EW Reunions Issue, visit ew.com/reunions. Fans can bid on memorabilia, meet-and-greet and more from some of the stars featured in the Reunions issue. Visit charitybuzz.com for more information.