Veteran comedian Phyllis Diller was taken to hospital after falling out of bed and injuring her neck and head.
Diller paved the way for many comediennes
The 87-year-old's manager said she was found by her housekeeper at her home in Brentwood, Los Angeles.
"She has a big bruise on her forehead," said manager Milt Suchin. "I think she blacked out."
Diller's career took off when Bob Hope saw her performing her stand-up routine in the 1950s, and she continues to perform in movies today.
She gave up doing her stand-up show in 2002, mainly because of ill health.
Diller has been undergoing tests in hospital since her fall, including on the pacemaker which she had fitted in 1999.
The comic recently published her autobiography, Like a Lampshade in a Whorehouse, looking back on her career and her family life.
She had two husbands and five children, one who was a schizophrenic.
She has been hailed as a groundbreaker for female comics, paving the way for the likes of Lily Tomlin, Roseanne Barr and Ellen DeGeneres to hit the big time.
Among her film roles were three alongside Bob Hope, including Eight on the Lam and Boy and Did I Get a Wrong Number!
Her more recent screen credits include playing the voice of the Queen in A Bug's Life and the soon-to-be released Unbeatable Harold.
Diller was nominated for a Golden Globe for The Pruitts of Southampton in 1967, and has received a star on the Hollywood Walk of Fame.