Genial anchor Hugh Downs, one of America's most familiar TV faces, is signing off as co-host of ABC's newsmagazine "20/20" after 21 years.

Downs will continue to co-host the newsmagazine's Friday edition until the start of the new season in September, ABC said yesterday. His contract with ABC for television and radio ends in October.

"It is time for me to move on," said the 78-year-old Downs, who's celebrating his 60th anniversary in broadcast this month.

But not retire. Downs says he's planning something "in the context of new media," though he didn't say what.

For the first 17 years of his 43-year television career, Downs worked for NBC on such classic shows as "Caesar's Hour," "The Tonight Show," "Today" and the classic game show "Concentration."

The son of Akron, Ohio, began his broadcast career at the tender age of 18 as a radio announcer in Lima, Ohio. After a stint in the Army, he joined NBC in Chicago as a staff announcer and in 1954 went to New York to co-host, with Arlene Francis, NBC's pioneering magazine show "Home." He hosted the final season--1956-57--of NBC's classic program "Caesar's Hour," starring comedy great Sid Caesar as well as Carl Reiner and Howard Morris.

In the summer of '57, he helped launch "The Tonight Show" with Jack Paar; he stayed with the late-night strip as announcer for five years. And yes, it was a startled Downs who had to wing it when host Paar walked off the show during his monologue after being censored by NBC the night before for using the term "water closet."

(Thirty-seven years later, Downs would do his own walkout on "20/20" when co-host Barbara Walters interviewed fallen sportscaster Marv Albert one month after Downs said on Larry King's CNN show that neither he nor Walters would do that interview.)

In August '58, he became host of the daytime game show "Concentration," taking on the prime-time emceeing duties three years later.

In September 1962, Downs made one of broadcast TV's more unusual career segues, from the game-show circuit to host of NBC News's "Today" show, reporting each morning on the day's news and interviewing world leaders. During his nine-year career there, he also reported and narrated a number of NBC News documentaries and specials, including "The American Wilderness" and the Emmy Award-winning "The Everglades." He left "Today" in October 1971.

One of his most controversial career moves was taking on the anchor chair of ABC News's "20/20" in June 1978, when its two co-hosts were dropped less than a week after the newsmagazine's premiere. Walters joined as co-anchor in 1984.

The Guinness Book of World Records certified him in 1985 as having logged the most hours on network commercial television.

"There is a reason for that," said ABC News Chairman Roone Arledge. "His warmth, intelligence and his common sense have endeared him to generations of viewers."

Both at "Today" and at "20/20," Downs paired up with Walters. It is that 37-year relationship Downs says he'll miss most.

"The longest personal association I've enjoyed in the business is with Barbara Walters," Downs said yesterday. "The pleasure of working with her stretches back to 1962, when she wrote and produced the segment that welcomed me onto the 'Today' show at NBC."

Said Walters, "I am proud that my partnership with Hugh is one of the longest and most successful in television history. Hugh is a gentleman in every way."

News yesterday that Downs was hanging it up in September fueled speculation that ABC will at that time drop one edition of its "20/20" newsmagazine, which now airs four nights each week. For the past few seasons, ABC and NBC have spread their flagship newsmagazines thick across their prime-time schedules. But newsmagazines command a lower ad rate than does entertainment programming, so both networks are likely to try to cut by one the number of editions on their fall lineups, with the understanding that the newsmagazine will move back into the slot if the entertainment show flops--or elsewhere on the schedule, as needed.

Executives at ABC and parent Disney are now screening entertainment series pilots for the 1999-2000 TV season. They are set to unveil their new schedule on May 18.

Family members of a slain gay man who are suing the producer of Jenny Jones's talk show have upped the amount they're seeking to $71 million.

The wrongful-death lawsuit may go to the jury today after more than five weeks of testimony from more than 40 witnesses in a Pontiac, Mich., courtroom.

Attorney Geoffrey Fieger, who accused the show of driving Jonathan Schmitz to murder Scott Amedure by humiliating Schmitz on a program about secret crushes, raised damage demands in the civil suit from $50 million, Reuters reported.

Fieger represents the family of Amedure, who was shot to death by Schmitz in March 1995, three days after the two appeared on a taping of "The Jenny Jones Show." In closing arguments yesterday, Fieger reminded the jury that Amedure's mother "told you how the smell of her baby was like an angel from heaven, and now he visits her at night with holes in his chest, smoke rising from the wounds," the Reuters report said. He said the show exploited guests to boost its advertising and syndication fees, and the Amedure family's only recourse is to sue for money.

James Feeney, lawyer for "Jenny Jones Show" distributor Warner Bros. and producers Telepictures, both units of Time Warner, told the jury that Schmitz alone was to blame for Amedure's death. He reminded the jury that Amedure's mother and a friend testified that Amedure told them days before dying that he had slept with Schmitz.

"You cannot begin or end your deliberations with the idea that what this case is about is cleaning up the talk show industry or making a statement or doing anything at all other than doing justice in this case," Feeney told the jury.

Schmitz is awaiting retrial on second-degree murder charges.

CAPTION: Co-host Hugh Downs is leaving ABC's "20/20" after 21 years on the prime-time newsmagazine.