According to Fox News, the 85-year-old judge initially went home after falling in her Supreme Court offices but was later taken to George Washington University hospital after experiencing "discomfort". She went to the hospital this morning and was admitted "for observation and treatment", the public information office adds.
Ginsburg fractured two ribs in June 2012 but did not miss work. She also battled cancer twice and got a stent in 2014 to open a blocked artery.
"I feel so strongly about the topic because I've seen first-hand how vital it is for all citizens to understand our Constitution and unique system of government, and participate actively in their communities", she wrote.
The 85-year-old justice, a heroine for liberals, has vowed not to retire while President Donald Trump is in office.
Ginsburg has developed a reputation for her toughness and strength, both because of her rigorous personal training sessions in the Supreme Court exercise room, and because of the strides she's made for gender equality in the workplace.
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Ginsburg has had a series of health problems.
If the president has the opportunity to fill Ms Ginsburg's seat because she resigns or dies, the change would be a nightmare scenario for Democrats.
It's too early for any word on Justice Ginsburg's path to recovery just yet - but definitely makes ya think.
Actress Alyssa Milano, 45, was one of the ones reacting to the news online, writing: 'Ruth Bader Ginsberg can have my ribs.
In recent years, she has gained celebrity status among progressives - who lovingly refer to her as the "Notorious RBG" - and was the subject a recent documentary, RBG.
Ginsburg, who was the second woman ever nominated to the Supreme Court, has become an icon for women's right movements and advocates.