Back at work after months of illness, the 86-year-old nun had travelled to Rome to meet Pope John Paul II and to witness the taking of vows by new members of her Missionaries of Charity order.
"It was her first voyage after her illnesses, an already long flight made longer by a stopover," said cardiologist Dr Vincenzo Bilotta, who has cared for Mother Teresa during previous visits.
"After a half hour, she felt better. She had brought four Indian children who are being adopted and she insisted on presenting them personally to the Italian adoptive parents," Dr Bilotta added.
Mother Teresa smiled and waved to crowds as she left the airport. She will have a check-up while in Rome, but, in the meantime, Dr Bilotta said, she appeared fit enough to see the Pope later in her stay. No time has been announced for the meeting.
It was the first trip abroad since a series of illnesses that kept her mostly confined to a bed or wheelchair.
Accompanying Mother Teresa was Sister Nirmala, who was elected in March to succeed her as head of the order.
Mother Teresa, winner of the 1979 Nobel Peace Prize, began the Missionaries of Charity in 1947. Now it has more than 4,000 nuns and runs 517 orphanages, homes for the poor, Aids hospices and other charity centres.Reuse content