Maria Troncatti was born on February 16, 1883 at Corteno Golgi, a farming village in the Val Camonica above Brescia. She entered the Daughters of Mary Help of Christians, the Salesian Sisters, on October 15, 1905 and made her first vows at Nizza Monferrato on September 17, 1908.
In the First World War she nursed the wounded as a Red Cross sister at Varazze on the Ligurian coast. Caught in a flood there, she promised that if she lived she would ask to go to the missions. She lived, and asked.
On November 9, 1922 she sailed for Ecuador with Bishop Domenico Comin, and on December 4, 1925 reached Macas, in the forest of the eastern Amazon. There, and at Méndez, Sucúa and Sevilla Don Bosco, she spent the rest of her life among the Shuar people. She had no medical degree, but the forest had no doctor: she was nurse, surgeon, orthopaedist, dentist and pharmacist, and she opened one small dispensary after another. When she saved the daughter of a chief who had been wounded by gunfire, the Shuar gave her the name that stuck, Madrecita — little mother.
From 1934 to 1938 she was sent to Guayaquil to run a welfare institution, then returned to the forest. In 1954 the hospital she had worked for at Sucúa, the Hospital Pío XII, opened, and in 1961 she founded a maternity ward. She took the side of Shuar women, insisting that marriages be freely chosen and not arranged, and she taught forgiveness where revenge was the rule.
Her last years were spent trying to make peace between the Shuar and the settlers pressing into their land. She offered her life for that peace. On August 25, 1969, aged eighty-six, she boarded a small aircraft at Sucúa bound for Quito, where she was to make a retreat; the plane came down shortly after take-off and she was the only person killed. Her tomb is in the Salesian sisters' chapel at Sucúa.
Pope Benedict XVI declared her heroic virtues on November 8, 2008, and after the recognition of a cure attributed to her she was beatified at Macas on November 24, 2012 by Cardinal Angelo Amato; the apostolic letter of beatification fixed her feast on August 25. On November 25, 2024 Pope Francis approved a second miracle, and on October 19, 2025 Pope Leo XIV canonised her, naming her in his homily among the new saints who were 'evangelizers and missionaries'.