Pope John Paul II has made a brief appearance at his window to greet Palm Sunday pilgrims as he continues to recover from throat surgery last month.
The Pope's appearance was silent but symbolic
He was cheered by thousands of the faithful as he silently waved an olive branch from the window.
For the first time in his 26-year papacy, the Pope did not officiate at the Mass that begins Holy Week, the most solemn time of the Christian year.
He watched it on TV in his apartment overlooking St Peter's Square.
Various Vatican cardinals will stand in at Holy Week ceremonies, but the Pope has insisted he will still deliver the traditional Easter Sunday morning blessing and message.
The Pope has essentially lost the ability to speak in public as a result of the inexorable progress of Parkinson's disease, says the BBC's David Willey in Rome.
Top cardinals who have seen him recently assure the faithful that the pontiff can still utter a few words and carry on a limited conversation with visitors.
But the third longest papacy in history has now entered its final phase, says our correspondent, with a pope who has to use modern communications technology - video and radio links - to manifest his presence at public ceremonies.
The Pope's doctors have told him to avoid contact with crowds, as he has a high risk of infection with a breathing tube in his throat.
The tube was inserted by doctors last month when the pontiff underwent a tracheotomy because he was having difficulty breathing.
The procedure was carried out at Rome's Gemelli Hospital, where he had earlier spent 10 days suffering from similar flu-related symptoms.