Actress Dame Elizabeth Taylor is being treated in a Los Angeles hospital for symptoms of congestive heart failure, her spokesperson said.
The 78-year-old was taken to Cedars-Sinai Medical Center on Friday for the "ongoing health problem", spokesperson Sally Morrison said.
Her condition remained unchanged on Saturday, Ms Morrison said.
Dame Elizabeth has a long history of medical problems and underwent heart surgery in 2009.
"Her family and close friends are appreciative of the warm support and interest of her loyal fans but have asked that people respect her privacy and allow her medical team the time and space to focus on restoring her back to health," a statement issued on Friday said.
The actress had been scheduled to attend an award at a benefit gala for HIV/Aids charity amfAR on Wednesday in New York, but missed the event.
An award given in recognition of her support to HIV/Aids work was accepted by Sir Elton John on her behalf.
Dame Elizabeth won best actress Oscars for Butterfield 8 in 1961 and Who's Afraid of Virginia Woolf? in 1967.