SAN DIEGO (AP) _ Singer Margo J. Sylvia, best known for her hit song ''Happy, Happy Birthday Baby'' with the 1950s group the Tune Weavers, has died at age 55.

Sylvia died Friday from a heart attack and stroke at Hillside Hospital, said Maena Bell, her granddaughter.

''Happy, Happy Birthday Baby'' became a gold record in August 1957, reaching No. 3 on the rhythm & blues chart and No. 5 on the pop chart. It was the Tune Weavers' only hit.

Sylvia later worked as a solo performer around the country. She moved to San Diego in 1990 and was scheduled to sing in four California cities in mid- November on a concert tour with other 1950s singers entitled ''The Golden Voices Of Rock 'N' Roll.''