She was still blowing a hot tenor sax in 1981 on Johnny Carson's "Tonight Show" and, later, on the NBC sitcom "The Golden Girls."
"The first time I picked up a sax, I said, 'This is it!' I loved the feel of it -- free and loose," she said in a recent interview. And the instrument played a starring role in her 95-year career.
Gilbert, who was born in Iowa and lives in Studio City, is nearly 102. But her memories remain as fresh as the day in 1912 when she made her stage debut, dancing a Scottish fling at age 7.
By the time she graduated from a Sioux City, Iowa, high school in 1923, she was playing the saxophone in her five-piece, all-girl band.
She arrived in Hollywood in 1928, at age 23, playing in hotels, nightclubs, radio, movies and television.
During the Depression, "as a joke, two friends of mine, male musicians, dressed in drag trying to get a job with my band," she said. "It was just like in that movie 'Some Like It Hot,' " starring Marilyn Monroe.
Although it was rare for male musicians to dress as women, it wasn't unusual for a woman to dress as a man to play in an all-male band that wouldn't accept women, Gilbert said.
"It wasn't until World War II that women musicians were accepted to play with male bands," she said.
So women played on their own. Jeannie Pool, a music historian and cultural preservationist who wrote and produced the new documentary "Peggy Gilbert and Her All-Girl Band," said: "There were so many all-girl bands in the 1920s and 1930s that one group of women got together to spoof the all-girl bands, calling themselves the 'Kitchen Band.' They played with eggbeaters and spatulas, anything they could find in the kitchen drawer.
"But Peggy has seen it all, done it all and has plenty to say about life and music," Pool said.
Music is entwined with Gilbert's DNA. Her father was a violinist and conductor of the Hawkeye Symphony Orchestra in Sioux City; her mother was an opera singer. Born Margaret "Peggy" Knechtges on Jan. 17, 1905, she had a piano waiting: Her parents bought it for her before she was born.
When she was 7, a Scottish minstrel named Harry Lauder hit town for an engagement. Gilbert's third-grade teacher had taught her and six other girls to dance the Highland fling in authentic costumes. Lauder was so impressed that he took the girls along on a summer tour through the Midwest. The other performers looked after the girls.
"My parents didn't worry," Gilbert said. "They knew the business required traveling and believed I needed to learn how to do it. We loved it."
Soon, she was playing the piano with her father's string and wind groups. But her heart was set on playing the saxophone. Her brother played the drums, and her high school boyfriend played the sax.
"Not that I wanted to best him," she said, "I just liked it."
But girls weren't allowed to play wind instruments in the school band -- only the "womanly" violin, piano and harp. So she took sax lessons from a local bandleader.
She played her first sax gig with her brother Orville's band in 1926, when she was 21.
Soon she started her own band, the Melody Girls. They played for club dances and hotels in the Midwest. "I wasn't trying to be a star, just make a living," she said.