"HOLLYWOOD," says rookie producer Keith Barish, "is probably the last bastion of the true so-called American entrepreneurial system."

Barish should know: He's one of the freest enterprises going, an enfant riche who in 1979 showed up in show biz with nothing more than a passion to master the movies and a personal fortune in eight figures.

He lost no time: In a two-year-buying flitz, the 36-year-old real-estate tycoon has invested over $5 million in more than 20 film projects, including "Endless Love," starring Brooke Shields and directed by Franco Zefirelli, which opens nationally next month.

He has further rocked the reel world by acquiring the rights to books generally regarded as too "literary" for the tarnished silver screen including William Styron's best-selling "Sophie's Choice" ($750,000) and D. M. Thomas' current best seller, "The White Hotel," ($500,000) along with a host of somewhat less cerebral projects, including Robin Cook's "Brain" ($750,000, William "Exorcist" Friedkin to direct).

"This is a business of personal opinion," he says with the ex-cathedra certainty of a Selznick-seized veteran. "And one reason that films have not been successful in Hollywood recently is that people are afraid to express their opinions, and are just guessing at what the public will want."

In that climate, many producers live in a perpetual acid-bath of aggravation that would strip the stomach lining off a shark. But as he leans back into the muted velours of his suite at the Georgetown Inn, Barish's boyish face and the aggressive modesty of his blue blazer and rumpled tan slacks seem miscast for a man who works in the gee-whiz jungle of packaging pictures: acquiring properties, finding directors, contracting for screenplays, locating studios willing to develop the materials and actually make the movie.

Like most executive producers, he receives a fee from the studio ("anywhere from $100,000 [for 'Sophie's Choice'] to $350,000 -- which is a lot of money if you're not taking the risk of buying the material"), as well as percentage "points" on future earnings from the film. But unlike all but a few cinema sheiks, he makes the initial investment. "Many people in Hollywood talk a good game but they never put up their own money. I do."

Conventional film-world wisdom says that only one movie in 10 makes money -- once an attractive prospect for developers seeking tax shelters under looser laws. But now, Barish says, "with all the economic disadvantages, you either ought to believe passionately in what you're doing or just not do it." He reads all potential purchases himself, is content to make his company "essentially a home for directors," and generally stays out of productions details. "Many people take exception to my theory of the business. But when you're developing as many projects as I am, you just can't be on the set making sure that the camels show up."

Not everyone is impressed with Barish's eclat. "There's a natural resentment in this town toward people who haven't paid their dues," says one veteran studio executive. But many newcomers make good -- most notably shopping-center developer Mel Simon, who produced "Love at First Bite" and "The Stunt Man," among others -- and no one is accusing Barish of overselling himself. He gives a few small dinner parties, and socially "keeps a fairly low profile," according to one longtime Hollywood watcher.

On July 17, that profile will rise considerably with the opening of "Endless Love," complete with Diana Ross' soundtrack album, a Polygram tie-in. Barish calls the project "a textbook case of something that goes right." Scott Spenser's novel of adolescent lust and obsession was a hot property in the film community, but Barish outbid the competition and was able to attract the celebrated Zeffirelli, who planned to cast two unknown leads as he had in "Romio and Juliet." A "perfect" male (a valet car-parker named Martin Hewitt) turned up in the first tests, but after countless cattle calls across the country, Zeffirelli had not found the girl.

"Then Jon Peters at Polygram suggested Brooke Shields." Barish had "some reservations," fearing that the 15-year-old might be only a "media phenomenon." But the screen test convinced him, and Polygram got a waiver to work during the actors' strike ("although," he grumbles, "we had to close down filming in December for two weeks while Brooke had final exams"). "So in a little less than a year," Barish says, "The project went from a book to a film in production."

For "an interesting example of how things can go wrong," Barish offers the melancholy tale of "Revelations," Phyllis Naylor's 1979 novel about the romance and travail of a young fundamentalist woman in the modern South. Sally Fields was interested in the novel, but no one would back it. Enter Barish, who bought the rights and hired Waldo Salt ("Serpico," "Midnight Cowboy") to convert the book. "He started writing the screenplay adn then he had to have open-heart surgery and he lost his wife to cancer." Salt's expected six months of labor turned into 12, "and in the end the screenplay didn't work, I'm sure because of the personal problems." But director Jack Clayton "did a miraculous job working with the script," and since the Paramount project has a summer setting, Barish wanted to start filming next month. But now, with the threatened directors' strike, "We might not be able to shoot at the earliest until summer of '82, with the earliest possible release in '83."

He recounts these stories with such palpable pride that it is hard to take him seriously when he waves a gold-watched wrist and says, "I'm not interested in business any more." But then, to hear him tell it, he never really was.

Born in Los Angeles, he moved to Miami at the age of 3 when his parents divorced, and as he grew up developed a prodigious interest in politics, working on the campaign of Rep. Claude Pepper (D-Fla.) and serving as a White House intern in 1962 after high school. He came away impressed by "one of the ideas Kennedy had brought in: If you have money, it's easier to go into politics and be independent." So he majored in government and business at the University of Miami, but left after his third year to join a group of businessmen forming a new bank. That in turn led to "real estate, which in Florida was undergoing a terrific boom."

In the mid-'60s, he became one of the original investors in Gramco, a vast mutual fund that was "one of the early companies which encouraged foreign investment in the U.S. through real estate." Among the founding directors was Pierre Salinger, former JFK press secretary, and the operation included a number of other ex-Camelotians who saw a new frontier in real estate. The company ran into problems in the early '70s, after the Robert Vesco scandal caused a brief panic in other overseas-investment plans, and the management of the fund was finally sold to a New York firm.

But Barish -- who had been living in New York since 1968 -- had left the company in 1971 in favor of private speculation. "The way I made most of my money," he says," was buying land in Florida when nobody wanted it. J. P. Morgan used to say, 'You don't buy straw hats in the summer.'"

He became seriously rich, but in 1977 experienced a mid-wealth crisis: Real estate, he realized, "does not require a great amount of foresight, and I didn't particularly find it challenging any more. I woke up one day and said: Look, I can't do this for the rest of my life. I'd hate to see my obituary with nothing but my net worth.

"I'd always loved movies, but didn't know a thing about them, didn't know anybody in the business." So he flew out to Hollywood, checked into the Beverly Hills Hotel, and set out to learn. "A friend introduced me to Leon Kaplan, the dean of motion-picture lawyers. I asked him to represent me and introduce me to anyone in the business who had anything interesting to say."

Barish formed a company and soon was up to his Rolodex in rubbish: "We had screenplays thrown at us, stuff that hadn't been made for 15 years, weird tax deals, remakes of old Sonja Henie films. I though, 'If this is why I'm here, I should just stick to real estate.'" He considered the horror and comedy market, but felt it was "equally absurd to do B and C films that were nothing more than business deals."

But at that point, Stan Kamen of the William Morris agency (director Alan Pakula's agent, and now also Barish's) came to Barish with a prepublication copy of "Sophie's Choice," an investment which had proven about as inviting as swamp land among the major-studio satraps. "Too downbeat," Barish says. "After all, when Nathan and Sophie commit suicide, it's not exactly your fairy-tale Hollywood ending."

barish read the book, and then called a number of people "asking for advice. They all told me not to do it, that it would never get made." But Pakula ("Klute," "All the President's Men") was "obsessed with the story," Barish says, and wanted to do the screenplay himself. "He thought it was the most important literary property he had ever seen. And I felt the same way." So Barish took the plunge, knowing "I could lose and have nothing to show for it but a very expensive coffee-table decoration." A month later it was a best seller, and suddenly studios were interested. But Barish, aware that many properties are bought but never made, chose Lord Lew Grade -- not previoulsy handicapped with a highbrow reputation -- because "he had never made this kind of film, and it would become one of his most important."

Barish makes no pretense of being a long-time lover of good literature, and often buys a book because a star or director already has expressed interest in it. But he intends to make his mark with a certain kind of property. After the "Sophie" deal, "I decided I would never do anything but material of that kind again," and even when submissions to his office "increased 20- or 30-fold," Keith Barish Productions kept investing in quirky, literary and unproven projects, including Rhea Kohan's "Hand-Me-Downs" (Jack Clayton directing); Alfred Bester's science fiction classic "The Demolished Man"; several other novels; original screenplays by Scott Spenser and Joe Eszterhas; Dennis Hamill's upcoming novel "Machine," a roman a cleft about Brooklyn politics; the Gretchen Cryer musical "I'm Getting My Act Together and Taking It on the Road" and Dennis McIntyre's 1978 play, "Modigliani," to star Al Pacino.

As a condition of purchase, Barish requires "matching funds with the publisher to advertise the book as a book, since "in many parts of the country, people would think "The White Hotel" is a place in Atlantic City and 'Sophie's Choice' is the Sophie Tucker story." And he tries to allow authors as much participation as possible (Cook is writing his own screenplay, and Pakula consulted Styron extensively on "Sophie"). But many Barish properties will be transformed en route to the screen. "The White Hotel," he says, "will serve to inspire a film"; and "Getting My Act Together" will make "the interesting nucleus of a film. It wouldn't work as is, but what we have in mind can."

Barish also has invested in a little real estate for himself: a three-bedroom house in Bel Air where he lives with his wife Ann, 33, and son Christopher, 7. "The tour buses say that Judy Garland lived in the house, but I know she didn't because I've seen the title report." Barish felt little culture shock at the West Coast transplant, although he was at first surprised by how the "all-consuming" business of making movies wears people out. "We gave a dinner party one night, and by 11:15 everyone was gone. My wife and I looked at each other, wondering if we'd said something wrong."

As he settle in to cinema, Barish expects to avoid the dream traps of Hollywood. "I don't see this business as some ego game akin to Monopoly.I think there are much better ways to get your ego stroked. Pakula told me once, 'If you want ego gratification, get it at home.'"