Alex Chilton, the mercurial leader of the Box Tops and Big Star who burst from the Memphis, Tenn., music scene in 1967 singing "The Letter" in the smoke-gravel voice of a grizzled soul man even though he was just 16 at the time, has died. He was 59.

Chilton was pronounced dead in the emergency room of a New Orleans hospital Wednesday after complaining of shortness of breath and chest pains, longtime friend Pat Rainer said Thursday. The cause of death has not been determined, but Rainer said Chilton's wife, Laura Kerstin, said he appeared to have suffered a heart attack.

Big Star was scheduled to play a reunion performance Saturday in Austin, Texas, at the annual South By Southwest Music Conference. John Fry, owner of the Ardent Studio in Memphis where Chilton recorded with the Box Tops and Big Star, said Thursday that the other band members had decided to proceed with the show as a tribute to Chilton. "You can't throw a rock at South By Southwest," Fry said, "without hitting someone who was influenced by Big Star."

Originally, Big Star's fans numbered not in the millions, but in the hundreds, perhaps thousands. Like the Velvet Underground, Big Star's influence developed well after the band no longer existed, influencing acts from R.E.M. and the Posies to the Bangles and Teenage Fanclub.

Eventually, millions did hear at least one Big Star song, "In the Street," used as the theme song for the Fox TV comedy series "That '70s Show."

William Alexander Chilton was born in Memphis on Dec. 28, 1950, one of four children of Sidney and Mary Chilton, musicians who immersed their children in music, both recorded and live, often hosting jam sessions at home.

After performing in a talent show at Central High School, Chilton was drafted for the Box Tops and coached by producer Dan Penn toward the gritty, soulful vocal style that turned their recording of Wayne Thompson's song "The Letter" into a nationwide hit that spent four weeks at No. 1, when Chilton was still 16.

"Cry Like a Baby" reached No. 2 the next year, and the Box Tops charted eight other songs in the Top 100 before the group disbanded out of frustration over not being able to record the band's own material.

Not long after the demise of the Box Tops, Chilton fell in with guitarist Chris Bell, bassist Andy Hummel and drummer Jody Stephens and formed Big Star. "Big Star is like a vulnerable Beatles," Counting Crows lead singer Adam Duritz once said. "They sing about all those dreams that you had when you were young that got broken. I'm not sure people were ready for that music back then. It was very confused and vulnerable music, and it was great."

But none of the group's three albums _ "1 Record," "Radio City" and "3rd/Sister Lovers" _ ever cracked the Billboard Top 200 Albums chart. That was partially responsible for sending Chilton into a psychological tailspin, and he spent the next decade in a haze of alcohol and drugs.

Still, the influence of what he'd done with Big Star was felt in the bedrooms and garages of aspiring musicians around the country, to the extent that Rolling Stone magazine once proclaimed, "It's safe to say there would have been no modern pop movement without Big Star."

Chilton returned to music, recording and performing sporadically, but to him, the up and down life path was preferable to sacrificing his musical vision.

"I've always done what I wanted to do or what I thought was best for any given moment, but it was never what people expected or thought they wanted," Chilton said. "Staying true to your own vision is the only thing I can do. It's hard to say in general about career moves, but I'm kind of happy where I ended up."

In addition to his wife, Chilton is survived by a son, Timothee, from his first marriage; and a sister, Cecelia.