What happens if a pope is too ill to serve? Church rules, past letters and the facts as of October 2026

There is no formal rule. Canon law makes no provision for a pope being incapacitated by reason of health, either temporarily or permanently, and it does not specify which body has the authority to certify that the pope is incapacitated. It states only that when the Roman See is vacant, or completely impeded, no innovation is to be made in the governance of the universal Church. What it does allow is resignation: if the pope resigns, the resignation must be made freely and properly manifested, but need not be accepted by anyone.

So popes have made their own arrangements. According to Cardinal Giovanni Battista Re, a longtime curial official, Pope Paul VI handwrote two letters in the late 1960s or 1970 in anticipation of an incapacitating illness, and in 2018 a letter of his dated 2 May 1965 was published. Pope John Paul II wrote a letter in 1989 offering to resign if he became incapacitated; in 1994 he wrote that he could resign only in the presence of an incurable illness or an impediment, and he continued in office. Pope Francis confirmed that early in his pontificate he had prepared a resignation letter in case illness impeded his work. That letter was never enforced, and he died in office in 2025.

The most recent illnesses are a matter of record. In February 2025 Francis entered Gemelli Hospital in Rome with bronchitis and stayed for more than a month, after a polymicrobial infection of his respiratory tract and bilateral pneumonia. He was discharged on 23 March. He died on 21 April 2025. The seat was then vacant, a period called sede vacante, from 21 April to 8 May 2025, during which the normal authority of the pope is suspended and limited governance is carried out according to church law.

As of October 2026, the reported facts about the current pope, Leo XIV, are these. During the Angelus prayer on 11 October 2026 he announced that he had a lung nodule that would be removed within the following week. After the surgery on 13 October it was reported that the nodule showed signs of adenocarcinoma, the most common lung cancer, and that the lower lobe of his right lung had been removed.