Pope John Paul II has returned to his apartments in the Vatican after two months at his summer residence, Castel Gandolfo, in the Alban hills outside of Rome.
The Pope waved to pilgrims and tourists as he passed
The 83-year-old pontiff's health has been causing particular concern after he cancelled his weekly general audience in Saint Peter's Square on Wednesday because of an intestinal problem.
A Vatican spokesman said the Pope planned to resume his normal engagements almost immediately - during the next few days he will be celebrating a mass commemorating the 25th anniversary of the deaths of his two immediate predecessors and receiving the president of the Philippines.
Vatican officials had insisted that the Pope's stomach ailment was not serious, but correspondents said the Pope has cancelled his general audience at short notice only a handful of times during his 25-year papacy.
The Pope suffers from Parkinson's Disease and also from painful arthritis which means he is now immobile and has to use a specially made wheelchair disguised as a throne at papal ceremonies.
His speech is often slurred and his hand trembles, but he is determined to continue in office as long as he is able and refuses to contemplate retirement from what the Catholic Church has always considered a job for life.
The pontiff waved to the handful of tourists and pilgrims who greeted him as he drove into St Peter's Square, just after nightfall.
The BBC's Rome correspondent, David Willey, says next week the Pope will be meeting the head of the Anglican communion, the Archbishop of Canterbury at the Vatican.
Mother Teresa plan
And October looks like being a very busy month with the beatification of Mother Teresa, a meeting of cardinals from all over the world and celebrations marking the Pope's silver jubilee, he adds.
On Wednesday the Vatican's number two, Secretary of State Angelo Sodano, presided over the audience in place of the pontiff, reading the speech and welcoming pilgrims.
The Pope spoke to the pilgrims by a telephone link from his summer residence near Castel Gandolfo near Rome.
In a frail voice, the pontiff said how sorry he was not to be there, his words trailing off towards the end.