A presidency spokesman said the checkup at a Pretoria hospital was a scheduled visit so doctors could manage the 94-year-old former president's existing conditions, the South African Broadcasting Corp. reported.
"Doctors are conducting tests and have thus far indicated that there is no reason for any alarm," spokesman Mac Maharaj said.
"We appeal for privacy for Madiba and his family."
Mandela was hospitalized in December for a recurring lung infection and later had gallstones removed, the SABC said.
Mandela, the first black South African president, served from 1994 to 1999. He fought for decades to end the country's apartheid system, serving years in prison. He was awarded the Nobel Peace Prize in 1993.