"The Oprah Winfrey Show" is a big deal for syndication -- especially for national advertisers -- pulling in nearly $160 million per year. Where will Oprah advertising dollars go after she leaves the air in September 2011?

Some analysts believe the show could remain in syndication with other similar TV talk shows. Others believe it could head to cable.

With the overall national syndication marketplace at $4.2 billion in 2008, according to TNS Media Intelligence, Oprah Winfrey's piece of the market amounted to around 4.0% of all syndication national money.

This came from the three minutes of national advertising time in the daily one-hour show sold by CBS Television Distribution. (Her show was double run in many top markets, which added to her total gross rating points for national advertisers).

"The Oprah Winfrey Show" took in $158.8 million in 2008, according to TNS Media Intelligence. The year before, the show had $158.9 million in ad revenues. For the first six months of 2009, the show pulled in $69.9 million -- down a bit from the $81.3 million for the first six months of 2008.

Much of the Oprah Winfrey show dollars were tied to the most desirable daytime demographic -- women viewers 25-54 -- and to a lesser extent, women 18-49.

But Oprah's ad deals were like no other: She could get a premium because of her strong association with products and services -- stuff that was promoted in her show directly, as well as for those marketers who just bought straight-ahead 30-second commercials.

Marketers say being attached to Oprah in any way felt like she was personally endorsing products.

"That is part of her appeal," says Brad Adgate, senior vp and corporate research director of media buying agency Horizon Media. "It's what advertisers really like about her, and what viewers really like about her."

CBS Television Distribution could retain much of Oprah Winfrey national advertising dollars, since it controls highly rated afternoon talk shows targeting similar daytime women demographics --"Dr. Phil," "Rachael Ray," and "The Doctors", for example.

But a lot will also depend on what big market ABC TV stations that run "The Oprah Winfrey Show" -- and who have profited handsomely from the show for over two decades -- do with her prized time slot.

"It depends on who becomes anointed as her successor," says Bill Carroll, vice president and director of programming for station sales representative Katz Television Group.

Carroll says ABC may decide to run an existing syndication talk show -- or start up a new one. That alone will give it a head start. Just by habit, he says, viewers will be drawn to Winfrey's long-time 4 p.m. time period on the East and West Coast (3 p.m. in other time zones).

Syndication isn't the only alternative for Oprah sponsors. Adgate says: "A lot of [Oprah Winfrey's advertising dollars] will move to cable." He says this because cable's audience continues to grow there. And with cheaper pricing for those programs, advertisers could shift their media plans.

Carroll believes the new cable network, OWN: Oprah Winfrey Network, could also benefit from following Winfrey herself to her new TV home.

Adgate also says that cable TV shows are a bit more open when it comes to new and closer advertising/marketing agreements -- something marketers increasingly expect with TV media deals.