LOS ANGELES (AP) _ Hollywood agents and producers are watching the Kim Basinger trial with growing fascination and dread as the show business tradition of handshake deals comes under fire.

The actress and her talent agency are defending themselves in $6 million- plus civil lawsuit over Basinger's failure to appear in the film ''Boxing Helena.'' Closing arguments are scheduled to begin Monday morning.

Testimony during the four-week trial has offered a rare and occasionally embarrassing inside look at Hollywood's dealmaking and excess. Basinger was to receive as much as $3 million to act in the movie, a story of obsessive love eventually made with actress Sherilyn Fenn.

But it is the strategy mounted by attorneys for Basinger and her talent agency that has prompted the most interest. Specifically, agents and producers uninvolved in the case are startled by a defense claim that only a signed ''Boxing Helena'' contract for Basinger would have been legally enforceable.

''Basinger may win this case, but the very people who need most to have a binding deal based on an oral agreement - talent agents - will be hurt the most,'' said one agency lawyer, speaking on condition of anonymity.

Said Karl Mazzocone, the ''Boxing Helena'' producer who brought the lawsuit, ''They have to impeach the way they do business themselves to win this case.''

Hollywood has long operated on oral agreements and handshake deals, with only one studio - the Walt Disney Co. - insisting on signed contracts. Actors rarely sign written agreements; at one point, Basinger signed her name on just two of nine movie contracts.

Typically, performers or their agents are given verbal offers to star in motion pictures. Representatives for the actors and the producers then negotiate ''deal memos,'' usually a few pages long, highlighting compensation and employment conditions.

Longer contracts are drafted, but rarely signed.

In the ''Boxing Helena'' case, the film's producers and Basinger's attorney exchanged half a dozen contract drafts over a three-month period. None were signed, but it appeared to the film's producers Basinger intended to act in the independently financed movie.

Mazzocone and his attorneys say the 39-year-old actress promised she would do the film. Basinger also wrote a ''Boxing Helena'' song, called the screenplay ''magical,'' and suggested a costume designer for the film, according to testimony.

On the eve of the film's production, however, Basinger said she was unhappy with the screenplay and would leave the project unless she was granted a script approval clause.

The film's makers sued Basinger and talent agent International Creative Management for breach of contract.

Defense attorney Howard Weitzman says the actress never agreed to star in the film. Since a written agreement was never signed, she was not legally bound to provide acting services, he says.

''That she was ever going to do the film defies logic,'' he said. ''They could not have reasonably expected that she would act in this picture.''

But a variety of agents and producers said the exchange of deal memos and draft contract agreements sends an opposite message: You don't start negotiating unless you're going to work, they say.

''Of course you have a deal even if you don't have a signed long form,'' said a top producer, speaking on condition of anonymity. ''If everybody had to wait for a signed long form agreement, nothing would ever get done.''

One studio attorney says that if ICM wins the Basinger case with this defense, he can turn around and use it against the agency to renege on handshake deals.

''I absolutely am loving this,'' the attorney said. ''I can now say, 'We don't have a signed deal, I don't owe your client anything. Your own agency argued in court that only signed deals are enforceable. Sorry.'''

Julie Philips, an attorney who worked on several drafts of Basinger's contract, testified that without a signature the actress ''did not have an obligation'' to act in ''Boxing Helena.''

Philips' own law firm, though, is asking Mazzocone in a separate disagreement to pay its client, actor Ed Harris, $600,000. Once cast in ''Boxing Helena,'' Harris was to be paid whether he acted in it or not.

There's one catch, however.

Harris did not have a signed contract.