Old men with hats pulled down over their bald heads sat by the hour, lost in the swirling, sweaty crowd, painstakingly translating into Russian passages from the Bible before them.

Elsewhere, middle-aged men, better-dressed and wearing official badges or carrying red official invitations, milled among the myriad books about high technology and advanced science, carefully recording in their notebooks complex formulae from scientific tomes.

At still another booth, teenagers wearing jeans pressed together like sardines in a can leafing eagerly through a heavily-thumbed history of the Beatles. Eyes wide at every page, they occasionally scribbled a note from the book chained to the wall.

This was the scene at the second Moscow International Book Fair, an event of extraordinary meaning in a country starved for contact with the world outside and possessed of abiding love for good books on any subject in any tongue. The huge exhibition, spread through two large halls at the International Exhibition Grounds north of central Moscow, ends tomorrow after a one-week stand playing to tens of thousands of Russians eager for tastes and sights of civilizations beyond their own closed borders.

Shy in the face of so many foreigners and sensitive to the constant pressure of grim-faced plainclothes agents and self-important Soviet officials, the Russians nevertheless pressed forward, wearing their innocence on their sleeves and ready for their hopes to be crushed at any moment.

"I love James Bond the secret agent," declared a teenager with a confidential grin. "Where is the author Fleming?" But then he conceded he had never read a word of the famous character's famous adventures. When told the books at the fair were on show but not on sale, he drifted into the crowd without another word.

"I would like to buy this book," the elderly man said. He clutched tightly to his chest an illustrated history of Hollywood, his face wreathed in the smitten grin of a man who may have just seen his first Rita Hayworth publicity photo. Again, dismay and instant resignation when informed the books were not for sale.

But not all Russians were so easily persuaded that not for sale meant not for taking. Despite rigorous searches of all parcels, bags and packages leaving the exhibit halls, most publishers reported wholesale losses to the light-fingered and adventuresome Soviets willing to run the risk of getting caught with a foreign book.

Among the 20 U.S. publishers with booths here, plus the large Association of American Publishers' exhibit of more than 3,000 titles, the quickest to disappear were books on sports -- not surprising in a sports-loving nation.

But, more inexplicably, other titles disappeared as well, including two books from the Minneapolis House of Lerner publishers, called "Careers in a Department Store," and "Self-Defense," a book about karate and other martial arts.

To many non-American publishers as well as some U.S. firms here, the difficulties several American houses have experienced over censorship of some of their books by the Soviets seemed unnecessary, messy, and -- worst of all -- bad for business. For these publishers, censorship began at home. "Stupid to bring such stuff in," remarked one British representative.

Indeed censorship problems predominated in the so-called "tradebooks" area and not in the technical and scientific publishing areas, where the Soviets are eager to buy and sell, and where most of their precious hard currency for purchasing rights to foreign books goes.

While the chairman of the Association of American Publishers, Doubleday Vice President Alexander Hoffman, said the U.S. firms must carefully review their future participation in the fair in view of visa problems, virtually every dissident writer here believes the Americans should continue showing up at future book fairs.

Dr. Andrei Sakharov, in an interview in his apartment last week, remarked that "fifteen years ago, such a fair would have been unimaginable" in the Soviet Union. He concluded that the Americans had "acted with dignity" by protesting both the confiscated books and the refusal of a visa for Random House Books head Robert Bernstein, and that, regardless of these problems, the lives of Muscovites had been enriched by the fair.