The hot rock 'n' rollers of this humid nation came out Sunday night to dance in the aisles of the Karl Mark Theater here and all but prove the declarations of thousands of American parents and politicians in the 1950s: Rock is subversive.

Since Thursday, when six American groups arrived here for the first Cuban-American music festival since the revolution, their biggest complaints have been about the audiences, which tend to be over 30 and preponderantly from government positions. Few in the theater the first two nights -- and even fewer in the streets of Havana -- are even familiar with the names of the musicans.

On Sunday, however, after an hour of Xavier Cougat-like music from the Orquestra de Santiago de Chileanda and a mild reception for Kris Kristofferson, the younger audience began to crank up: first when Kristofferson dedicated in Spanish a song to Fidel Castro (who never made an appearance at the theater) that listed Castro, Che, Zapata and Christ as great revolutionaries, then even more enthusiastically when Rita Coolidge, Kristofferson's wife, launched into several of her hits. Obviously there is a large group of young Cubans plugged into American culture through Florida radio stations.

Sunday's was the final concert of the series, and the younger audience may have been lured by several Cuban artists on Sunday's bill: Sara Gonzalez, Pablo Milanes and the group Manguare, all of them part of the Nueva Trova (new song) movement in Latin America. Nueva Trova is akin to the American folk music of the early '60s, and Milanes is sometimes referred to as the Bob Dyla of Cuba.

Indeed, this was one of the few political notes of the festival. And though the songs of American musicians helped spark the American cultural revolution of the '60s, the singers have since become depoliticized, and here -- 10 years after Woodstock -- they are finding Cuban-style socialism an exasperating system to deal with. Taxicabs are scarce. Customs and changing money require large amounts of paperwork. Services in hotels are slow and costly. Cuba seems a relic of the hard times and frugality Americans have put out of mind.

If anything, the new political sensibility of the Americans here is heavily drenched with humor; Jazz musicians standing around backstage and listening to Richard Pryor tapes, or Billy Joel saying, "We wanted to put big posters of John Lennon and Groucho Marx behind us, but they told us that would be very touchy."

In the end, playing rock 'n' roll was the most political act Joel could perform. Halfway through his one-hour set Sunday night, the young people in the audience charged the stage. They were waving their arms in the air, dancing in the aisles, mouthing the words to some of the songs. By the end of the hour guards began the wings of the stage, but the fans ignored their exhortations for order to move out into the audience from and demanded an encore -- the only encore of the entire festival.

"I bet," said one American, "that you won't be seeing any more rock 'n' roll in Cuba for a long time."