Pope Francis underwent an operation on Sunday for an inflammation of the colon.
The pontiff reacted well to the surgery on the intestines in the Gemelli University Hospital in Rome, the Vatican said in the evening.
Accordingly, it was a "planned" operation.
Before that, the head of the Catholics had held the Angelus prayer in St. Peter's Square as usual.
In the afternoon, the pontiff, accompanied by his driver and a close colleague, arrived at the clinic and was operated on a little later, as reported by Italian media.
The Pope is to spend the next five days in the clinic to observe.
The 84-year-old Francis suffered from a stenosis due to diverticulitis, according to the Vatican.
This is a narrowing of the intestine as a result of a sometimes painful inflammation of the so-called diverticula, protrusions of the intestinal wall.
In the past, Francis had to cancel some public appearances due to health problems.
The Argentine-born Pope had part of his lungs removed at the age of 21 after pleurisy.
He has also been suffering from sciatica and hip problems for some time.
During his midday prayer in St. Peter's Square on Sunday, Francis announced a trip to Hungary and Slovakia in September.
In Budapest he will celebrate the closing mass of the Eucharistic Congress.
Although the exact travel program has not yet been determined, there is no evidence that Francis will meet representatives of Prime Minister Viktor Orban's government during his short stay in Budapest.
The Pope had already announced his trip to Hungary in March and emphasized that it would not be an official state visit.