ALL Yu Jin has to do is switch on her keyboard, lean into a few notes, and she has defied etiquette in China with enough daring to make Madonna seem like Mary Poppins.Unlike Madonna, Ms. Yu feels no compulsion to flaunt sacrilege or to flounce about the stage in gold lame lingerie. Yu and other members of Cobra, China's first all-woman rock-and-roll band, break plenty of ironclad proprieties simply by tearing into a few roaring bars of classic Rolling Stones. Cobra is arguably the freest and boldest force for feminism in a country where the state-controlled "women's movement" is as restrained and predictable as a garden club meeting. "The traditional concept for what women in China should do is to give birth to children and cook," says Wang Xiaofang, Cobra's drummer. "Chinese people traditionally don't think women can achieve anything, but I think we can achieve a lot," she says, sweeping her palm through a head of spikey black hair tinted brown at the tips. Even members of all-male rock groups belittle Cobra because of the gender of its members. Although many of China's male musicians trumpet a defiant message, they ironically fail to appreciate Cobra's own feminist iconoclasm. "A lot of men who play rock-and-roll despise us and say there's no way we'll play well," according to Yu. "But after hearing us, many of them have changed their minds and accepted us," she says. Cobra's social overtones have offended not just sexists but also officials from a totalitarian regime that deems any group beyond its control a potential enemy. Like other rock groups in Beijing, Cobra performs with the threat that officials will pull the plug on their act at any time. The band last year stirred up a Beijing concert audience so much that its first large public performance turned out to be its last. "It is as if my feelings were burning and I could even hear the wonderful sound of my blood flow as it went gurgling on," the magazine "Women's Friend" quoted a young woman as saying after the concert. Officials have indicated that the band is unlikely to gain approval to play before a large audience again, says Yu. Appropriately, Cobra was conceived during the euphoric Beijing Spring in 1989. It made its first music soon after the massacre of pro-democracy activists that June, as the vast police apparatus seized dissidents nationwide. But band members claim they came together not because of discontent with state repression but because of a loathing for the state-approved, kitschy renditions of Chinese folk songs. All but one of Cobra's members have spent years with state bands, playing pat versions of folk songs over and over again on the accordion, dulcimer, piano, and erhu, a bowed instrument with two strings. "I love folk songs played from the heart that truly express the feelings of the Han people," says Yu. "But the songs I played with the state group lacked life; I can express myself with Cobra," she says. Yu quit the China Light Music Ensemble in June to spend more time leading Cobra. Jeffrey Cheen, an American music producer based in Hong Kong, says that the band's biggest contribution to music could be in how it adapts Chinese folk songs and traditional instruments to rock. Cobra plays a handful of traditional songs like "Riding Horses on the Mountain," a Sichuan love song, by harmonizing the melodies and prodding the tunes with a rock beat. The band stands tall as a symbol of defiance by playing at full volume songs by the Beatles, Dire Straits, and other groups whose music is officially viewed as part of a capitalist conspiracy to subvert socialism. Government leaders apparently allow the music of Cobra to continue as a raucous counterpoint to the incessant drone of state propaganda. Band members say that because their repertoire is already controversial, they do not feel compelled in their own songs to strike directly at issues that are politically proscribed. So when Cobra sings about China, it condemns people's passive acceptance of repression but shies away from calling for widespread activism. In one piece in three-part harmony, Cobra rebukes conformity under socialism but backs away from suggesting the political alternative: Just like a madman in his own private heaven, I'm satisfied, I don't have to be the same as others. I don't need grain tickets or money for food and clothes, And I don't have to be the same as them, I don't need a bed to sleep on. I'm satisfied and healthy. Just like a madman in his own private heaven. But in at least one song, Cobra tweaks the turned-up noses of China's veteran revolutionary leaders. The band routinely plays "Nanniwan," an old Communist Party anthem extolling Brigade 359, the unit led by senior leader Wang Zhen during the revolution. But Cobra does not sing the lyrics Brigade 359 is the model, let's go forward and give them fresh flowers to the steady, trite beat familiar to Chinese. Instead, the band accents the offbeat by playing the song in reggae. "Maybe Wang Zhen would be touched if he heard us play the melody," says guitarist Xiao Nan with a grin. "Yes, after all we're making rock-and-roll with Chinese characteristics, along the path of socialism!" says Ms. Wang the drummer with a giggle, lampooning a maxim of paramount leader Deng Xiaoping.