Pope Francis was doing well on Monday after surgery for an inflamed large colon, but the 84-year-old was expected to spend around seven days recovering in hospital, the Vatican said.
The pontiff was admitted to Rome's Gemelli hospital Sunday for a scheduled operation under general anaesthetic for symptomatic diverticular stenosis of the colon.
Francis "is in good general condition, alert and breathing spontaneously", spokesman Matteo Bruni said in a statement, adding that the surgery "lasted about three hours".
"A stay of about seven days is expected, barring complications," he said.
A week earlier, on the eve of the feast of Saints Peter and Paul, Francis seemed to hint at the upcoming operation, saying: "I ask you to pray for the pope, pray in a special way. The pope needs your prayers."
The pontiff had already put his Wednesday general audience on hold for the summer, and has no other official appointments in his calendar until Sunday, when he is due to lead the Angelus prayer.
Italy's Prime Minister Mario Draghi sent Francis "affectionate get well soon wishes" on Monday. Sheikh Ahmed el Tayyeb, the Grand Imam of Al-Azhar, one of the Muslim world's leading authorities, wished the pontiff "a speedy recovery".
Francis is in the same suite on the 10th floor of the Gemelli hospital used by Pope John Paul II.
The late pope underwent surgery there seven times, including after an attempt on his life in 1981, and for a tumour in the colon in 1992.
The suite has a bed, television and ensuite bathroom, as well as a little sitting-room with a sofa bed and a small altar, according to the ANSA news agency.
The corridor housing the suite is guarded by Italian and Vatican police, it said.
John Paul II was there so often that he dubbed the suite overlooking the Gemelli entrance "Vatican 3", third in line after the tiny city state in the centre of Rome and the papal summer palace at Castel Gandolfo, outside the city, it said.
Francis's condition causes potentially painful inflammation of the diverticulum, a pocket that can form on the colon walls and which tend to multiply with age.
"Stenosis" here means an abnormal narrowing of the colon, and patients with diverticulitis may experience lower abdominal pain, fever or rectal bleeding.
The condition may be caused by high pressure within the colon or a diet low in fibre and high in red meat, according to the American Society of Colon and Rectal Surgeons.
The Vatican said Francis underwent a left hemicolectomy, in which the descending colon -- the part attached to the rectum -- is removed.
The remaining bit of the colon is then attached directly to the rectum.
The pontiff had arrived at the clinic in the afternoon accompanied by his driver and one close aide, and Italian media said he was in the operating room a few hours later.
Born on December 17, 1936 in Argentina, Francis lost part of his right lung at the age of 21. He also suffers from a hip problem and sciatica.