Pele has been admitted to hospital for a "medical evaluation" after cancelling his appearance at an event in his museum.
The Albert Einstein hospital in Sao Paulo did not disclose why the Brazilian football star was admitted, saying in a statement only that he would "undergo exams".
The private Agencia Estado news service and other local media said the 74-year-old was suffering from stomach pain, but his condition was not serious.
The city of Santos earlier in the day said that Pele had cancelled his appearance at the Pele Museum because of "health reasons".
It was not clear if Pele would remain in hospital. No other details were immediately available.