His death was confirmed on the band's Web site. No cause was given, although Mr. Topol had struggled with alcoholism since his youth.

Mr. Topol first performed in 1978, when he was 13, at a gathering of dissidents at the country retreat of the playwright and future Czech president Vaclav Havel. He opened for the band Plastic People of the Universe, whose members had become a cause célèbre after being imprisoned.

The following year, Mr. Topol and two friends formed Psi vojaci (pronounced psee voh-YAH-tzee), taking their name, which means Dog Soldiers, from fierce Cheyenne Indian warriors in the Thomas Berger novel "Little Big Man." Mr. Topol's older brother, Jachym, a poet and playwright, wrote some of the band's early lyrics.

Mr. Topol was among the youngest signatories of Charter 77, a dissident document released in 1977 that called on Czechoslovakia's Communist government to respect human rights.

After a performance outside Prague, Mr. Topol underwent the first of several interrogations by the Czechoslovak secret police over his rebellious lyrics. His mother, Jirina, had to accompany him because he was only 14 at the time.

The band was forced underground, able to play only in remote locations for audiences gathered by word of mouth. Recordings were passed around illicitly on cassettes.

Mr. Topol's concert performances could be so furious that his fingers would bleed on the keyboard. He said he saw the piano as a wild horse that needed to be broken. Of his lyrics, he said, "I wanted to make music so dark, even the Commies would slit their own throats."

Mr. Havel himself introduced Psi vojaci on stage at an anniversary concert, saying he had been proud to have ushered them into the underground movement. When they played the Knitting Factory in New York in 2000, a reviewer wrote in The New York Press, "They play music that leaves an almost unbearable ache in your chest, honest music you rarely hear outside the blues."

Filip Topol was born on June 12, 1965, the son of Josef Topol, a poet and dramatist, and the former Jirina Schultzova.

With the collapse of Communism and Mr. Havel's election as president, Mr. Topol was able to quit his job as a computer programmer and devote himself fully to music, poetry and writing. The band released its first two albums in 1991. Some 20 more followed, including solo projects by Mr. Topol. The band's last performance was in Amsterdam on May 25.

Mr. Topol wrote several novels, three of which, written in the 1980s, were to be released in June under the title "Jako pes" ("Like a Dog").

He is survived by his parents and brother.

Mr. Topol came to see that the efforts of the state to fragment, isolate and crush dissidents had an unintended effect, that by driving them underground the authorities actually strengthened their solidarity.

"It was an unbelievably beautiful schooling," he said. "During that time we enjoyed the kind of friendships you read about in old books. The underground was a ghetto where people stuck together."