Earl Scruggs, the Grammy Award-winning musician whose innovative bluegrass banjo work was heard in the theme music to the television sitcom “The Beverly Hillbillies” and the movie “Bonnie and Clyde,” died March 28 at a hospital in Nashville. He was 88.

Mr. Scruggs’s son Gary confirmed the death to the Associated Press. He did not provide a cause. In a career spanning six decades, Mr. Scruggs won acclaim as a virtuosic instrumentalist who helped transform the reputation of the banjo through dynamic playing and public exposure through film, TV, record and radio.

Mr. Scruggs’s flashy, three-fingered banjo style was a new sound to most audiences when he joined the popular band Bill Monroe and the Bluegrass Boys in 1946. Mr. Scruggs’s technique expanded the melodic possibilities of the instrument, putting it on equal footing with the fiddle and mandolin. He also succeeded in changing the reputation of banjo players as comic relief — they had often been portrayed as clowns — to that of skillful soloists.

The late 1940s version of the Bluegrass Boys, with Mr. Scruggs, guitarist Lester Flatt and fiddler Chubby Wise is widely regarded as the first group in the bluegrass style — a style built on the group’s vocal harmony and the interplay of Monroe’s mandolin with Mr. Scruggs’s banjo.

“In the three year period of 1945 to 1948, the banjo assumed a prominence in Monroe’s music that it had never enjoyed in any previous band,” wrote country music historian Bill Malone. “Throughout the nation, largely unnoticed by the more commercial world of country music, a veritable ‘bluegrass revolution’ got underway as both fans and musicians became attracted to the music.”

With fellow Monroe sideman Flatt, he formed Flatt and Scruggs and the Foggy Mountain Boys in 1948. Their recordings of the theme to the television sitcom “The Beverly Hillbillies” and the instrumental “Foggy Mountain Breakdown” (1950) — heard during the car chases in the 1967 film “Bonnie and Clyde” — brought bluegrass its greatest recognition.

Self-taught musician

Earl Eugene Scruggs was born Jan. 6, 1924, in Flint Hill, N.C., a tiny farming community. He was 4 when his father died, leaving Mr. Scruggs and his five siblings to tend a farm with their mother. Everyone in the family played music.

“I was raised with a banjo and a guitar and an autoharp,” he once told The Washington Post. “I came up at a time — we were poor in the country — when we didn’t have a radio, so everything I did was self-taught.”

Mr. Scruggs and his two brothers taught each other timing by starting a song and then walking in opposite directions as they played. They would do this until they played in time with one another when they regrouped.

His early musical influences included a local banjo player Snuffy Jenkins. Bluegrass historians credit Jenkins with developing a picking style using three fingers of his right hand. Mr. Scruggs knew Jenkins and, while acknowledging his influence, always maintained that he learned the three-finger roll on his own.

“When I was about 10 years old, I was just sitting there daydreaming with the banjo in my hand, and all of a sudden I was doing a three-finger roll, which metered out just fine. I played everything that I knew, and I played it so much until I learned little things to add to it myself,” he once said.

He joined the Morris Brothers’s string band in 1939, performing on the radio in South Carolina, then quit music to work in textile mills during World War II. He resumed performing in 1945 with old-timey performer “Lost” John Miller on WSM in Nashville.

Around this time, Mr. Scruggs came to the attention of Bill Monroe, whose Bluegrass Boys performed on the nationally broadcast “Grand Ole Opry.” Monroe hired Mr. Scruggs to replace his banjo player, Dave “Stringbean” Akeman, who played in the older clawhammer style and functioned as the band’s comic relief.

Unlike Akeman, Mr. Scruggs didn’t clown onstage but would smile stoically while he unleashed a torrent of notes.

Mr. Scruggs made his recording debut with the Monroe group in 1946 on “Heavy Traffic Ahead,” a song inspired by the hectic pace of the group's road work.

“Sometimes we would do what was called ‘bicycling,’ ” Mr. Scruggs once said. “We would play a show in a theater, and while the movie was on, go play in another and come back to the first one while the movie was on in the second. . . . It was a must, then, to make it back to the Opry on Saturday night.”

“We played in rain,” he added, “we played in snow, we played where the power would go off, and we would have to play by lantern light with no sound. We had two bad wrecks, but nobody got hurt. The way we had to drive to make dates, it’s a wonder we weren’t killed. But we made it, and it toughened you up to encounter and overcome these difficulties.”

Frustrated with the grueling schedule and Monroe’s parsimony, Mr. Scruggs quit the Bluegrass Boys. He planned to return to the textile mill but was approached by Lester Flatt about starting a new group, the Foggy Mountain Boys. The new group secured a radio show on WCYB in Bristol, Tenn., in 1948 and signed with Mercury Records. That same year, he married Louise Certain, who became the group’s manager.

By the mid-1950s, the group had a nationally syndicated television show through the sponsorship of Martha White Flour. They joined the cast of the “Grand Ole Opry” in 1955.

Flatt and Scruggs’s style differed from the Monroe style. Lester Flatt’s vocals were smoother than Monroe’s piercing nasality. Mr. Scruggs also encouraged the fiddler and mandolinist to stop playing during his solos for a less busy sound.

They added Josh Graves on the dobro, a type of steel guitar. Mr. Scruggs felt that the dobro’s mournful sound was suited to waltzes and slow songs and contrasted nicely with the relentless up-tempo drive of the banjo.

Gaining exposure

However, it was Mr. Scruggs’s banjo instrumentals that gave the band its reputation, notably with “Foggy Mountain Breakdown.” A 1968 re-recording of the song won a Grammy that year for best country performance. For “Flint Hill Special” (1952), Mr. Scruggs created a slurring effect like a steel guitar by turning the string’s tuning peg. The trick became part of the song’s melody, and Mr. Scruggs later added extra tuning pegs to the banjo to make the de-tuning easier.

Mr. Scruggs “bicycled” almost as much with his own band as he had with Monroe. While driving back from Nashville in 1955 to visit his mother in the hospital, Mr. Scruggs dislocated both his hips and fractured his pelvis in a car wreck. His wife, also in the car, needed plastic surgery for her face. He started flying his own plane to shows. Flatt occasionally hired Curtis McPeake as a substitute when Scruggs’s injuries would flare up.

In the late 1950s, Columbia Records marketed Flatt and Scruggs to the collegiate folk-music audience on long-play, or LP, records — a necessary strategy as bluegrass was losing favor with country radio. They performed several times at the Newport Folk Festival and recorded a live album at New York’s Carnegie Hall in 1962.

Their widest exposure came from “The Beverly Hillbillies,” a CBS sitcom that aired from 1962 to 1971. Actor Jerry Scoggins sang the theme song, “The Ballad of Jed Clampett” (1962), to Flatt and Scruggs’s accompaniment. The group appeared on several episodes although the producers had to allay their concerns about its rural stereotypes.

“That was the best shot we ever lucked up on,” Mr. Scruggs told The Post in 2000. “When they first contacted us about doing the theme, Louise turned it down because the show was called ‘The Beverly Hillbillies,’ and she was leery of how the show’s writers might depict Southerners. . . .But they convinced us that these rural people would be country intelligent, that they would outsmart the bankers and the city dudes by using common sense. And that was mainly what they stuck to in the script.”

Flatt and Scruggs broke up in 1969. Flatt, a conservative, didn’t see eye-to-eye with Mr. Scruggs’s politics nor with his song choices. Flatt continued working with the other former Foggy Mountain Boys as the Nashville Grass until his death in 1979.

Performing with sons

Mr. Scruggs formed the Earl Scruggs Revue with his three musician sons, employing what he termed a “no-cubbyhole, category-free, barrier-less approach to music.” They broke from traditional bluegrass with their electric instrumentation and a broad repertoire that included material by Bob Dylan and the Rolling Stones. A jam session years earlier with rhythm-and-blues saxophonist King Curtis had whetted Mr. Scruggs’s interest in playing other musical styles.

The band released several albums and toured until 1980, when back problems sidelined Mr. Scruggs.

Two sons who performed in the band, bassist and record producer Gary Scruggs and guitarist Randy Scruggs, both of Nashville, survive Mr. Scruggs. Another son, Steve Scruggs, the Revue’s drummer, died in 1992. According to a prosecutor, he shot and killed his wife, then shot himself.

Mr. Scruggs’s wife, Louise, died in 2006.

Mr. Scruggs, who received a National Heritage Award from the National Endowment for the Arts in 1988 and a lifetime achievement Grammy in 2008, performed with less frequency after a sextuple-bypass in 1996. He appeared with Doc Watson and Ricky Skaggs as the Three Pickers in a televised concert on PBS in 2003.

Throughout his career, Mr. Scruggs spoke of the importance of breaking musical boundaries.

“If you don’t let things develop, it’s like keeping something in a bag and not letting it out to fly,” he said in 2000. “There’s so many different types of music that you can put together to come up with a fresh sound. So that’s been the whole thing, to try to play something that sounded good. You never know until you try it out.”