Changing the face of television isn't easy. But leave it to Steven Bochco to try.

When his new medical series, "City of Angels," premieres Sunday at 8 p.m. on CBS, it will mark an attempt to launch one of television's most rare forms of series programming -- a one-hour broadcast network drama with a primarily African-American cast.

The series arrives in the middle of a TV season that opened with the NAACP challenging the major networks to offer more racial diversity in their programming. The networks responded by hastily adding some African-Americans to casts and promising more in the future.

With Bochco, one of television's most distinguished producers, behind it, the success or failure of "City of Angels" may determine the fate of other shows with minority-driven casts.

For now, though, Bochco is focused on the present -- and the past.

"This is something I've wanted to do for a long time," said the Emmy Award-winning producer, adding that it was during production on his hit 1981 police drama "Hill Street Blues" that he came up with the idea.

"I was so struck by what an extraordinary talent pool of black actors and actresses there is, and the extent to which it is simply underused because there just aren't enough good roles to go around."

"Angels," which moves to its regular slot Wednesday at 8 p.m., stars Blair Underwood and Vivica A. Fox as high-powered doctors at an inner-city Los Angeles hospital at risk of losing its accreditation. Because it is hampered by a lack of funds, staff shortages and outdated equipment, the hospital's struggle to save itself becomes even more precarious.

Equally precarious is the show's chance of survival. No African-American drama has ever succeeded on network television. Bochco acknowledged that viewers historically have tuned out such programs.

"It's the resistance that any of us might have, including black people, to being preached at," he said.

Bochco added that among some white viewers, "there's a somewhat more rabid resistance to watching anything that seems to empower black people in mainstream culture."

Bochco has joined creative forces on "Angels" with Paris Barclay, an African American who is the show's co-creator and one of its co-executive producers.

Barclay, an award-winning director whose work has included episodes of Bochco's "NYPD Blue" series, remains optimistic about audience response to the series.

"I think most people recognize that beneath the skin, we're pretty much the same," he said. "I could be wrong, and I'll be crushed, because I've underestimated the degree to which people are entrenched in their ways. But I'll be very surprised if this show doesn't work."

What may ultimately work in "Angels' " favor are Bochco's trademark storytelling devices: an ensemble cast, interlacing plotlines and romance.

Underwood plays Ben Turner, acting chief of surgery. Fox plays Lillian Price, the new medical director brought in to turn things around at Angels of Mercy Hospital. Price is also Turner's former fiance whom he jilted at the altar.

It is precisely this mix of the personal and the professional that most distinguishes "Angels" from African-American dramas of the past, including Fox's 1994 urban drama "South Central" and CBS's 1995 family drama "Under One Roof."

Indeed, prejudice notwithstanding, Bochco says that one reason most African-American dramas may have failed is that they focused on issues of race at the expense of more broadly appealing melodramatic themes.

"I've always thought the way to make any show successful is to be as story-intensive as you can be," he said. "So if you want to do a black drama, and have a chance at succeeding with it, do a black melodrama."

Despite "Angels' " racial makeup, Bochco added that race is not "a front-and-center issue" in the show.

"Our thrust here is not to make a television series about being black in America," he said. "It's to tell a story about a hospital whose predominant patient and staff population is African-American."

For Underwood, who first made a name for himself when he joined Bochco's hit series "L.A. Law" in 1987, "Angels' " subtle references to minority issues was one of the reasons he signed on to the series.

"As a black man, I can tell you that race is not the only thing we talk about everyday," he said. "Perhaps the faces in this series are a different hue. But that's just the canvas the story is thrust upon."

Even if race were to play a more prominent role in the series, Fox said the broad appeal both she and Underwood enjoy still would attract a large viewership.

"I don't think my audience or Blair's audience is just black," she said.

And like the 1997 hit movie "Soul Food," for which she is best known, Fox added that the quality of the series will hook those viewers.

"If a show is well-written, well-acted and well-directed, it will cross over to every audience that's available," she said.

Both Bochco and Barclay acknowledged that they won't ignore the issue of race either. But as it filters into some of the stories being told on the series, such topics will be dramatized in a manner that is sure to surprise viewers.

For example, Barclay noted that the subject of internalized racism -- the discrimination inflicted upon one stratum of the black population by another -- will be explored perhaps for the first time in a network series.

Tensions between white and black doctors in the hospital will also be examined. One story focuses on a beleaguered white resident who experiences the effects of reverse discrimination.

"He's the minority in this hospital," Barclay said, matter-of-factly. "It's a twist on the old story of the one black guy in the class who feels left out and confused."

Whatever role the issue of race plays in "Angels," it debuts at a time when the NAACP has placed increasing pressure on network television executives to diversify their ranks both on and off the screen.

Leslie Moonves, the president and chief executive officer of CBS Television, gave the green light to the series in March, months before the issue of diversity became a hot-button topic in Hollywood.

"It didn't just take the NAACP to make us realize that there weren't enough minority faces on television," Moonves said. "In a lot of ways, television has not done a good enough job of truly representing what the American landscape is. And as our culture becomes more diverse, I think it's important to reflect much more of the melting-pot nature of the country."

After months of heated debate, a great deal of which was played out in the press, the three other major television networks seem to agree with Moonves. Last month, the Big Four -- ABC, CBS, NBC and Fox -- avoided a threatened boycott by minority activists after submitting respective proposals to the NAACP to bring more diversity to the industry.

Even before the networks turned in those proposals, several minority dramas already had been in development for next season, underscoring the growing demand among viewers for more diversified programming on television.

By launching before next season, Barclay knows that "Angels" has become a test case for those other series.

"It's part of being looked at as the `Jackie Robinson of television,' " he said. "It's like a litmus test, and if it works, everyone will copy it. If it doesn't, they'll say, `Well, if Steven Bochco can't do it, nobody can.' "

Minority-driven, hour-long dramas have been high-risk programs in recent years. Such series as "M.A.N.T.I.S." and "413 Hope St." aired only a season, or less. Producer Dick Wolf used to point out that his mid-'90s series, "New York Undercover," was the only network drama series headed by a minority cast ever to have been renewed for a second season.

No one seems more aware of how much is riding on this show than Bochco himself.

"Television is a dollar-driven business, and when things succeed, everyone makes money, and everyone does it again," he said. "Should this show succeed, or even survive, it will make it easier for others. If it doesn't, I think it makes it harder."