MOSCOW - When prosecutors here recently threatened to file pornography charges against a post-modernist novelist, the writer accused them of trying to turn Russian society into a "castrated cat."

If so, they have set themselves a formidable goal. Russia seems as sexually unrestrained as any nation in the world. During the Soviet era, authorities tried to impose a prudish moral code on their comrades, outlawing sex and nudity in arts and literature. But in the end, they could no more rein in Russian libidos than they could crush the black markets.

Depending on your point of view, the collapse of Communist rule either ended 70 years of hypocrisy or unleashed a tide of sleaze, as sex came very much out into the open. Moscow has more than its share of raunchy nightclubs, strip joints and prostitutes. Sidewalk peddlers sell X-rated videos, and state-controlled TV stations broadcast films with nude scenes uncut.

Now, Russia's decade-old sexual revolution may be heading for some restraint. The Russian human rights commissioner has called for raising the age of consent from 14 to 16, and there is a move to strengthen laws against child pornography. Graphic movies are no longer broadcast in prime time.

"After the period when we didn't have any sex at all, we had a period of a sexual revolution," says Yana Lepkova, 26, a staff writer for the Russian edition of Cosmopolitan magazine. "This period has passed and has turned into some reasonable limits."

These moves are modest. Some religious and political leaders are trying to push the sexual counter-revolution further, urging abstinence outside marriage - a bold proposal in a culture where adultery has a long tradition, particularly among the powerful.

The Stalin-era law against homosexuality was repealed when communism fell. Now some deputies in the Duma, Russia's parliament, have proposed legislation to make it illegal again.

While new anti-gay laws are unlikely to pass, Russians increasingly seem to be drawn toward what some would describe as traditional values. "We are convinced that a true sex life is only possible in a family and can only be based on love," says Boris Yakimenko, a spokesman for the national youth group Moving Together.

The group, which staunchly supports President Vladimir V. Putin, launched a campaign this year against Vladimir Sorokin, author of a number of post-modernist novels. One work that drew its ire was Sky Blue Pork Fat, which depicts an imaginary erotic encounter between clones of Communist Party leaders Nikita Khrushchev and Josef Stalin. (The word for sky blue in Russian slang also means homosexual.)

Moving Together wrote to the Moscow prosecutor's office, demanding an investigation of the novel. It charged that Sorokin and his publishers violated Article 242 of Russia's penal code, which outlaws the distribution of pornography.

In June, the group staged a rally in downtown Moscow to denounce the author. At one point, the group placed a toilet bowl in front of the Bolshoi Theatre to protest its decision to commission Sorokin to write the libretto for a new opera.

Prosecutors recently agreed the book was pornographic and brought charges, but it is doubtful the novelist will ever be hauled into court. Sorokin, who refused to answer questions in a police interview this week, scornfully rejects the allegations.

"I have written, I am writing and will continue writing tough literature," he told a Moscow newspaper. "It will contain everything that exists in our lives - starting with love and ending with sex and violence."

Politics, as well as sex, may be fueling this cultural struggle. The main taboo that Sorokin broke may have been dishonoring the memory of Communist leaders, who remain popular with a surprising number of older Russians nostalgic for the Soviet Union of their youth.

While Russians pride themselves on their sophistication about sex, public discussion is considered "uncultured" - a Soviet-era concept deeply rooted in Russian society. For many nonreligious Russians, being uncultured is the equivalent of committing a mortal sin.

From books, magazines

Sex education is rare, banished from most public schools after a short-lived experiment in 1996 drew criticism from the Russian Orthodox Church. "We didn't learn much about sex in school," says Anastasia Vasiliyeva, 16, a high school student whose parents also did not discuss it with her. "What we know, we got from reading books and magazines ourselves."

Autumn M. Lerner, a graduate student in international studies at the University of Washington, recalls discussing sex with students in a Moscow nightclub a few years ago. She was shocked that what little they knew was wrong.

"Russian kids were denying there was AIDS in Russia," she says. "They denied that safe sex was important."

So Lerner decided to write her master's thesis on sex education here. She concluded that while young Russians lead very active sex lives, there is still a reluctance to discuss the topic. Many Russians are growing up sexually active and sexually ignorant.

"There's no tradition with which to talk about these issues," Lerner says. "Parents refuse to talk to children about it. Teachers don't talk about it."

Russia, she says, is locked in "sexual silence."

To Lerner and other sex education advocates, the consequences are predictable. According to UNESCO, the rate of syphilis among teen-agers exploded in the 1990s. While abortion rates have fallen drastically since Soviet times, two out of three pregnancies end in the procedure. And the United Nations recently reported that AIDS is spreading faster in the former Soviet bloc than any other part of the world.

Soviet propaganda tried to discourage use of the pill by emphasizing the risk of cancer. Today, one survey found, only 9 percent of Russian couples rely on the pill, about half the rate of the rest of the world. In the meantime, Lerner reports, some Russians use contraceptive methods that employ household soap and soft drinks.

The Soviets weren't always so dour. In the years after the 1917 revolution, women in particular pushed for more sexual freedom. Although Lenin had a mistress, he denounced attacks on traditional family values as "un-Marxist and anti-social." While talking about sex with one German revolutionary, he said: "The revolution demands concentration. ... It cannot tolerate orgiastic conditions!"

The real crackdown came under Stalin. Scientific research about sexual behavior was banned. Erotic imagery in art and literature was outlawed. Painters made sure to depict fierce-looking women in peasant blouses buttoned up to their chins. Homosexuality was prohibited as a capitalist vice in 1934. Abortion - legalized in 1920 - became illegal again in 1936.

Sex - like so much of Soviet life - went underground. In some intellectual circles, scandalous behavior became a form of protest.

'No sex in Soviet Union'

The official Communist line was that the Soviet Union had channeled the nation's sex drive into more serious pursuits. In 1986, one Leningrad woman declared in a televised debate that "there is no sex in the Soviet Union." About the same time, Dr. Lev Shcheglov, a Leningrad sociologist, reflected sadly: "What kind of orgasms do you expect in a society which, on top of all the shame we've loaded on sex, lived for decades in communal apartments?"

After the fall of the Soviet Union in 1991, Russians were jolted by the sexual revolution that had shaken the West 25 years earlier. As in the West, it has sharply divided generations.

"The kids in Russia are not afraid of sexuality," says Igor Kon, a sex education advocate and author. "They think it is natural, normal, interesting and pleasant. But government officials? Their parents? They believe it is very bad, it's dangerous."

He cited a proposed new law on child pornography. "We badly need the law," he says, "but in its definition of pornography, it says that everything that helps to promote adolescent sexuality should be banned. Can you imagine, for a teen-ager, anything that doesn't provoke sexuality?"

Young Russians aren't the only ones confused about sex. Dr. Mikhail V. Kuryakin, who specializes in impotence, says his middle-aged male patients typically suffer for a year or longer before seeking treatment. "This function is so meaningful for a man that he prefers not to talk about it, to hide it deep inside," he says.

Traditionally, men have turned to a variety of folk medicines - reindeer horn, seal penises and Siberian ginseng root - to cure impotence. But these "natural" cures are always discussed in general terms: exactly what they're supposed to do is seldom mentioned.

While quickly accepted in the West, Viagra was met with skepticism and hostility in Russia. Many physicians publicly questioned its safety and side effects, based on dubious or nonexistent evidence, claiming it could cause blindness or render users unable to perform without it.

Criticism of Viagra in the news media was so intense that some scientists suspect it was orchestrated by the herbal medicine industry.

But the drug gradually gained acceptance, and Kuryakin says it is one of the nation's top 10 in annual sales. Still, few want to talk about it. "Even if I took it, I would never admit it," growled one 40-year-old Muscovite to a female friend.

Anastasia Vasiliyeva's boyfriend is Sergei Koslovsky, 17, a physics student. As the couple sat together on a bench on Tsvetnoi Boulevard, Koslovsky recalled how a friend who tried to buy a sex manual was humiliated in a bookstore by scornful clerks.

Society can't afford to be so squeamish when its health is at stake, he says. "Quite many people do not want to discuss it at all," he says. "They think it's a dirty topic. But this should be discussed."