Hundreds of supporters sang and chanted pro-reform slogans to welcome home former United Nations nuclear chief Mohamed ElBaradei upon his arrival at Cairo's airport.
Mr ElBaredei has not lived in Egypt for decades but is understood to be considering running for the presidency next year.
ElBaradei was unable to leave the VIP lounge at the airport after his plane touched down from Vienna because of the crowds that gathered to celebrate his return today.
Many Egyptians hope the Nobel prize winner will challenge President Hosni Mubarak in next year's elections and usher in an era of democratic reform. President Mubarak has ruled for nearly 30 years, and appears to be trying to set up a political dynasty by grooming his son to succeed him.
Mr ElBaradei has said he would only join the race if guaranteed the elections would be free, fully supervised by the judiciary and monitored by the international community.