Muddy Waters, 68, the singer and guitarist who brought his brand of music from the Mississippi Delta to the urban north and to worldwide popularity, died of cardiac arrest April 30 in a hospital in Downers Grove, Ill. He lived in Westmont, Ill.

In 1980, he won a Grammy in the category of ethnic or traditional recording for "Muddy 'Mississippi' Waters Live." He sang "Mannish Boy" in Martin Scorsese's 1978 movie "The Last Waltz," which was based on a final concert by The Band.

His style called for a small number of musicians using maximum amplification. In that style, he led what was virtually the first electric blues-rock band, drawing talent from figures such as Jimmy Rogers on guitar, Little Walter on harmonica and Waters' half-brother, Otis Spann, on piano.

His 1954 blues tune "Rollin' Stone" inspired Bob Dylan's "Like a Rolling Stone," and also inspired the name of the Rolling Stones, who worked closely with the gruff-voiced Waters.

Mr. Waters' early musical influences included such famed bluesmen as Charlie Patton and Robert Johnson. In turn, Mr. Waters influenced a generation of English and American rock 'n' roll bands, including the Rolling Stones, who took their name from a Muddy Waters blues song.

The son of a sharecropper, he was born McKinley Morganfield in Rolling Fork, Miss. His mother died when he was three. He was raised by grandparents in Clarksdale, center of the Mississippi Delta and famed home of the blues. At age 15, Waters was leading his own quartet as a singer. In 1935, he started playing guitar. His mentor was Son House.

He picked up his nickname in his early days when he played at fish fries and other social gatherings in his hometown.

Mr. Waters left the Delta for Chicago in 1943. He worked in a papermill but sang at night in clubs on Chicago's South and West sides. He bought his first electric guitar in 1944 and shortly afterward was introduced to the Chess brothers, beginning an association of almost 30 years.

His first solo recording for them, "I Can't be Satisfied," convinced the Chess brothers that the brash, electrified blues sounds from the Delta were a commercial proposition and they set up Chess Records in 1950.

In the first half of the 1950s, Waters produced a series of passionate recordings. "She Loves Me" topped the R&B chart in 1952, followed up with classics such as "Hoochie Coochie Man," "I Just Wanna Make Love To You" and the blues-rock standard "Got My Mojo Working." Other hits were "Forty Days & Forty Nights," "Close to You," "I'm Ready" and "Mad Love."

Mr. Waters achieved national acclaim as part of a revival of American folk music, appearing several times at the Newport Jazz Festival in Rhode Island and at the Ann Arbor Blues and Jazz Festival in Michigan in the early 1960s.

The blues underwent a revival on college campuses and across England and Europe in the late 1960s, and white blues-rock guitarists, including Eric Clapton, and bands such as the Rolling Stones, Led Zeppelin and the Yardbirds found inspiration in his music.

Survivors include his wife, Marva, a son, Joseph, and three daughters, Mercy, Rene and Rosiland.