Vassilis Rapanos, who was named as Finance Minister in the new Greek government on Thursday, has not been sworn in to office yet.
His swearing in ceremony had been scheduled for Friday evening, but was postponed due to his illness.
Greece's incoming finance minister Vassilis Rapanos has been rushed to hospital after a fainting spell, said a government official and a source at the bank where he is chairman.
"He felt dizzy and fainted and was taken to hospital where he was given fluids intravenously and will undergo checks," the banking source said.
A government official said he spoke to Rapanos on the phone after he was taken to hospital, where he was in the process of undergoing checks.
Rapanos, the chairman of Greece's biggest commercial bank National Bank of Greece, has been named finance minister in Prime Minister Antonis Samaras's cabinet and was due to be sworn in later today.