A spokesperson said the 94-year-old was breathing without any problems. He had a procedure on Saturday to clear fluid in his lung area.
Mandela checked in to the hospital Wednesday night for the third time since December.
The Nobel laureate is a revered figure in South Africa, which has honored his legacy of reconciliation by naming buildings and other places after him and printing his image on national banknotes.
Under South Africa's white-minority apartheid regime, Mandela served 27 years in prison, where he contracted tuberculosis, before being released in 1990. He later became the nation's first democratically elected president in 1994 under the banner of the African National Congress, helping to negotiate a relatively peaceful end to apartheid despite fears of much greater bloodshed. He served one five-year term as president before retiring.
Mandela last made a public appearance on a major stage when South Africa hosted the 2010 World Cup soccer tournament.
The Associated Press contributed to this report.