Jewish men are all over American television these days, in hit shows like Seinfeld,' Northern Exposure' and Murphy Brown.' Why now? What kind of image are they conveying? And where are the Jewish women?

Fans of NBC's new sitcom "Mad About You" in which comedian Paul Reiser plays a Jewish New York documentary-maker married to a gentile Connecticut PR exec may have noticed that with every episode, Reiser's character seems to be growing less and less Jewish.

"I can't really talk," attests Faye Ann, an assistant to series producer Denny Jacobson, "but it's true. Paul doesn't want his character to have any religious affiliation. He won't talk about it to the press, and the show's writers are no longer allowed to bring it up in their scripts. No more Yiddish expressions! Someone mentioned the word haftarah' in a recent episode, and Paul ordered it out."

Once upon a time this kind of "ethnic cleansing" of a TV script would not have required explanation. What would have been baffling was how an avowedly Jewish character, like Reiser's Paul Cooper, ever got his own TV series in the first place.

In those days, the abundance of Jewish TV writers and producers adhered to the show-biz admonition to "write Jewish, and cast gentile." Their assumption was that the American heartland would not take to emotional urban types who talked with their hands and had a suspicious fondness for bagels and pastrami.

But as the current TV season attests, there's been a fundamental shift in attitudes in the 20 years since "Bridget Loves Bernie," a controversial show about an intermarried couple, was pulled off the air after just one season in response to protests by Jewish and Catholic groups. In these days of cable and syndication, prime time is increasingly populated by explicitly Jewish characters with names like Fleischman, Seinfeld, Stein and Barash.

There still aren't quite enough of these boob-tube Jews to make a minyan, but considering the paucity of Jewish leads in the past, the current handful seems like a deluge. Such mainstream publications as Newsweek and the Chicago Tribune have hailed the new prominence of Jews on network TV as a trend.

Industry insiders and media pundits have yet to agree on why this mini-boom is taking place now, or what, if anything, it means. Is this sudden proliferation of up-front Yiddishkeit a passing fad, an unlikely coincidence or a significant social phenomenon? Why are virtually each of these leading men romantically involved with non-Jewish women? And why, for that matter, are there no Jewish women in corresponding roles?

Peter Noah, producer of the recently canceled ABC sitcom "Anything But Love" starring ultra-neurotic comic Richard Lewis, dismisses the sudden ubiquity of Jewish prime-timers as a fad. He says performers like Lewis, Jerry Seinfeld and Paul Reiser play Jewish men on TV because they came to the medium with full-blown personas that they developed as stand-up comics and couldn't jettison their shticks without undermining their stage identities. Had they come to TV as equally talented non-Jews, Noah has no doubt that they would still have gotten their own series.

"No one got up one morning and said, Hey, wouldn't it be nice to cast a Jewish character,'" says Noah. "The phenomenon is tied to who these guys are as performers. But I also think it was convenient for them that the current generation of writer-producers is the first one that feels that maybe they want to represent something closer to who they themselves are."

Some TV executives who might once have winced at the mention of an avowedly Jewish TV character now regard such creatures as good for business. Cable may not have tangibly improved the quality of TV fare, but its "narrow-casting" approach, designed to appeal to specialized viewers, did wrest control of the market from the stereotype of a more generic middle-American audience. Cable's rise also means that ratings that would once have spelled a program's doom are now regarded as sufficient for survival, and the young, hip urban market likely to support "Seinfeld" or "Northern Exposure" is no longer scorned by advertisers.

Los Angeles Times TV critic Rick Du Brow cautions against regarding this apparent philo-Semitism as something new. The many Jews who work in TV may well be less sensitive about their ethnicity than their predecessors were, he says, and there's no doubt that Jews have been accepted into the American mainstream. But if you want to trace the roots of this process, he suggests, read Philip Roth or Joseph Heller, and watch the early movies of directors Woody Allen and Mike Nichols, or of actors Dustin Hoffman, Richard Benjamin and Elliott Gould.

"There's a saying that all good things come to TV when they die," muses Du Brow. "In many ways, this is just old hat."

Also old hat, unfortunately, is the alarming absence of Jewish women in similar roles. Only one show NBC's "Reasonable Doubt," which stars deaf actress Marlee Matlin as a crusading district attorney features a Jewish female character in the lead role. Jewish women are even hard to find in supporting roles, since almost all of TV's Jewish men yearn after, or are married to, gentile ice goddesses.

"Look, the Jewish guy with the gentile girfriend is just an easy place to go," says "Dream On" co-producer David Crane. "You get something comical in the dynamic. I don't know many writers whose lives actually reflect that, or any of the other shticks you see."

Producer Marta Kaufman has been involved in the creation of two pilots for prospective series "Couples" and "Family Album" that will feature Jewish women. She says that the Jewish men who work in television are either reflecting their own mixed marriages or, more frequently, are "living out their high school fantasies of marrying the prom queen."

Kaufman sees the real problem as a general lack of good roles for women. "Once we fix that, we can worry about getting better roles for Jewish women. You do it in tiny increments, one show at a time."

Finally, now that it's safe to be Jewish on TV, will the writers, producers and performers so inclined find anything worthwhile to say about it? It's hard to imagine, when so many of the young Jewish men and women who write and produce TV shows are themselves less than certain about what constitutes Jewish identity.

"I don't know what makes a character Jewish," says Kaufman. "I don't think thousands of years of history make you Jewish. I think there's a cultural identification, and some would say an elitism. Mostly it's a matter of voice, of tone and inflection."

Adds Michael Filerman, producer of NBC's "Sisters": "We can't really define ourselves. Some people say Jews are a race, but I don't consider myself part of a race. I compare myself to a Protestant, not, say, to a black. Let's just say I'm not assimilated, but I'm not a Beduin either."