When Howard Dratch was a boy, he and his brother David would leave their family's home in Bethesda and head downtown to the old Howard Theatre at Seventh and T Streets NE to hear the same variety acts that played the Apollo Theatre in New York.

"It was a big theater," he recalled. "It was important culturally. What I didn't realize at the time, when we went to see Smokey Robinson and the Miracles and Fats Domino and musicians like that, was that there was an infusion of Latin music into rock 'n' roll."

Like almost every TV viewer in the country, he had heard Cuban music from bandleader Desi Arnaz on "I Love Lucy" during the '50s. As a student at Bethesda-Chevy Chase High School, he fed the juke boxes at the old Hot Shoppes drive-ins on Connecticut Avenue NW and in Bethesda. He also patronized the Showboat Lounge at 18th Street NW and Columbia Road.

In the early '60s, a wave of Brazilian music arrived, bringing the bossa nova to Americans. And Dratch also made certain he got to Carter Barron Amphitheatre when Harry Belafonte came to town with his Jamaican folk music.

Then Dratch went off to college -- the University of Wisconsin at Madison, with graduate work at the University of California at Berkeley -- and spent his time studying history.

But he didn't forget the music or its roots. Years later, after a stint as a reporter, Dratch, now an independent filmmaker, pulled together his two interests into a three-part series, "Routes of Rhythm." The series, which tells the history of Afro-Cuban music, concludes Friday on PBS stations (10 on 32, 10:30 on 22/67, 11 on 26). Its host: Harry Belafonte.

In the decade that it took him to make "Routes of Rhythm," Dratch and his filmmaking partner, Eugene Rosow, went to Spain's Costa del Sol, villages in West Africa and Spanish colonies in the Caribbean.

They also went to Cuba, where they spent almost eight weeks filming in 1984. That was an uneasy time in Cuban-American relations. Dratch said that both governments were "cautious of the project."

But Belafonte, who brought the music of the Caribbean to the United States during the 1950s, had kept his ties with Cuban musicians and artists over the years when the governments were less than friendly. "Belafonte believes very much that musicians and artists can maintain relationships, lots of times when things are frosty on a political level," said Dratch.

When Dratch returned to Washington, most of his old hang-outs were gone. But he was there to pore over old film clips of Latin music in the National Archives and the Library of Congress, which employs a specialist in dance film.

"Latin music has a lot of rivers and streams," said Dratch, "but we focused the series on the Afro-Cuban. The Cuban influence is the strongest influence of Latin music. Most of the dance crazes have been Cuban. The influence of Cuban music has been enormous. Cuban music has influenced American music since the beginning of the century."

In assembling a team for their project, Dratch and Rosow, who had met as graduate students at Berkeley, went to musicologist Rene Lopez and photographer Les Blank. Blank, said Dratch, "has a fine reputation in terms of his ability to capture musicians on film."

Dratch and Rosow produced and directed the series and, with Linda Post, wrote the script.

For Dratch, "making a film series like this is another way of teaching history. In recent years, there have been a lot of immigrants in the United States. It's part of American history how immigrants brought their music; it's part of the growth of our country. One thing we've tried to show is that Latin music has been around for a while. It isn't just for Hispanics."

Dratch, whose PBS series about the CIA and foreign intelligence, "On Company Business," aired in 1980, remarked: "I've hung out with spies and I've hung out with musicians, and I far prefer hanging out with musicians."

"Routes of Rhythm" includes some 60 pieces of music from Gloria Estefan's "The Rhythm's Gonna Get You" to selections from Carmen Miranda, Perez Prado, Cal Tjader, Dizzy Gillespie, Xavier Cugat, Reuben Blades, Bo Diddly and even the Diamonds ("Little Darlin'") and Donald Duck ("Tico Tico").

The music is available on a two-record set based on the series' soundtrack, one called "Cuban Dance Party," the other, "A Cavalcade of Cuban Music." The series, from Dratch and Rosow's Cultural Research and Communication, Inc., in Santa Monica, Calif., will also be available on videocassette.