The Vatican said there was no cause for alarm over the health of Pope Francis after he suddenly cancelled a visit to a Rome hospital.
The Vatican's chief spokesman, Father Federico Lombardi said the pope would resume his normal activities tomorrow morning.
Earlier, the pontiff cancelled a visit to the hospital at the last minute due to what the Vatican called a "sudden indisposition".
The Vatican gave no immediate details about what, if anything, was ailing the 77-year-old Argentine pope.
The pontiff has cancelled a number of engagements in the past few weeks due to minor health issues.
The Vatican issued its statement at about the time the pope was to have arrived at Gemelli hospital to visit patients and say a mass.
People had already gathered at the hospital to await the pope, when the Vatican issued a statement saying Angelo Scola, Cardinal of Milan, would read a homily in his place.
Italian media said the pope had postponed the appointment because he was "very tired".
Earlier, he had given his daily mass at Santa Martain the Vatican, where he lives and held a series of audiences.
Users of Twitter, the social networking site where the pope's @Pontifex account has over four million followers, quickly wished him well, posting tweets including "Speedy recovery, Pope Francis" and "praying for the health of the pope".
The "popemobile" had arrived early at the Gemelli hospital and people had climbed on it to pose for photographs, Italian media reported.
The pontiff, who suffers from sciatica, or leg pain caused by a pinched nerve, cancelled a scheduled walk in a procession through the streets of Rome last week, a decision the Vatican said was made to conserve his strength for coming engagements.
He cancelled an engagement the week before due to a slight fever, but subsequently made a number of public appearances during which he seemed to be in good health.