LOS ANGELES - Singer Mary Wells, who in the 1960s had teenagers snapping their fingers to "My Guy" and other tales of love lost and found, died yesterday after a long bout with cancer. She was 49.

Miss Wells, who underwent surgery for cancer of the larynx in August 1990, died at the University of Southern California's Kenneth Norris Jr. Cancer Center, said her daughter, Stacy Womack.

She had been there for several months.

Along with Smokey Robinson, the Supremes, Temptations and Four Tops, Miss Wells helped break down the era's musical segregation.

In 1961 through 1964, she hit the Top 10 in the pop charts with "The One Who Really Loves You," "You Beat Me to The Punch," "Two Lovers" and her signature "My Guy," all written or co-written by Robinson, a fellow Motown Records star.

"In 1964, Mary Wells was our big, big artist," said Lucy Gordy Wakefield, Motown's first sales chief. "I don't think there's any audience with an age of 30 through 50 that doesn't know the words to `My Guy."'

Like many artists of the time, Miss Wells was naive about business in the music industry, longtime friend Maye James said yesterday in New York.

"They were beat out of a lot of money, Mary included. They were just signing contracts, they were so happy to be making music," James said.

Before she fell ill, Miss Wells continued to perform in clubs and in oldies revues.

"Money was always tight, so she always had to work. They were

struggling there for quite a few years," James said.

Miss Wells was born May 13, 1943, in Detroit. At 16, she approached Motown Records founder Berry Gordy hoping to sell a song and found herself signed as a performer as well.

"He said she could sing it, and she says, `Oh, I can't sing,"' said Esther Gordy Edwards, Miss Wells' personal manager at Motown and Gordy's sister. "Mary was our first big, big star."

The song, "Bye, Bye Baby," turned out to be "a hit right off the bat," Edwards said.

After leaving Motown, Miss Wells signed with 20th Century Fox records in 1964 and later recorded for Atlantic-Atco and Jubilee, but never approached her earlier success.

Miss Wells put her career on hold in the early 1970s to raise her children but began performing again in 1978 at clubs and revues around the country.

When Miss Wells was diagnosed with cancer, the two-pack-a-day cigarette smoker had no medical insurance and lost her modest home in Los Angeles when she couldn't pay the rent.

The Washington, D.C.-based Rhythm and Blues Foundation raised more than $50,000 to pay for her medical bills. Diana Ross gave $15,000, Rod Stewart and Bruce Springsteen $10,000 each and the Temptations $5,000.

"People say this is a cruel business - and it is," Miss Wells said shortly after her surgery in 1990. "But a lot of people in the business do have hearts."