Bill Clinton has been rushed to Columbia Presbyterian Hospital in New York, the same hospital in which he underwent heart surgery a few years ago in New York.
The former President was suffering from chest pains in his Harlem office, and his staff brought him immediately to the hospital.
Hillary Clinton is believed to be on her way to her husband's side at the hospital.
The former President has been keeping an extraordinarily heavy schedule, and has just returned from a visit to Haiti, his second in several weeks.
He has often spoken about the bad heart genes he has inherited from relatives, and since leaving the presidency, has been working out regularly and has lost considerable weight.