Pope Francis missed a step and fell to the ground as he was coming to an open-air altar to celebrate Mass at Poland's holiest shrine of Jasna Gora on Thursday.
The 79-year-old, walking deep in thought in his long robe, did not notice a step down and fell to the ground before the altar.
Priests around him rushed to help him up and straightened his robe.
The Mass proceeded as planned and the pope delivered a long sermon before tens of thousands of faithful gathered at the foot of the Jasna Gora monastery in the southern city of Czestochowa.
Pope Francis, who is visiting Eastern Europe for the first time, has hailed Poland's native son St John Paul II, who was the first Polish pope, as a meek and powerful herald of mercy on his five-day visit to the country.
He also praised the countless “ordinary yet remarkable people” who held firm to their Catholic faith throughout adversity in the former Communist-ruled nation.
During the outdoor Mass before tens of thousands, Pope Francis lavished praise on a legacy of steadfast Polish Catholic faith as he urged Poles to hold fast to their faith.
The Mass was held in celebration of the 1,050th anniversary this year of Poland’s acceptance of Roman Catholicism.
The baptism of a medieval king in 966 put the nation on course to be part of the Latin-speaking world, setting it apart from Orthodox nations on its borders.
Pope Francis is urging today’s Poles to stay united, as their nation is divided over such issues as how to view refugees and migrants, especially those who are not Christians.
He prayed before that Poles would have “the desire to leave behind all past wrongs and wounds, and to build fellowship for all, without ever yielding to the temptation to withdraw or to domineer”.
Pope Francis will have his first big meeting with the young faithful in a Krakow meadow on Thursday evening.
He made an unscheduled stop at a clinic to visit and pray for comatose Cardinal Franciszek Macharski, an-89-year-old retired prelate who had been archbishop of Krakow. Cardinal Marcharski had replaced Cardinal Karol Wojtyla in the post after the latter was elected pontiff and became John Paul II in 1978.
The Argentine pontiff earlier spent time at the Jasna Gora monastery shrine’s iconic image of the so-called Black Madonna and Child.