Lorenzetti (lōrān-tsĕt´tē), two brothers who were major Sienese painters. Pietro Lorenzetti, c.1280–c.1348, was first influenced by Duccio di Buoninsegna and Giovanni Pisano. His earliest known work, an altarpiece at Arezzo, already shows the impact of Giotto's style in its concern with profound emotion and simple grandeur of form. In Siena he painted, with his brother, several that have been lost. Pietro's altarpiece (1329) for the Church of the Carmelites is now in the Pinacoteca. His last works are the magnificent Birth of the Virgin (c.1342; Opera del Duomo, Siena) and an altarpiece for the Church of St. Francis at Pistoia (now in the Uffizi). Of uncertain date are the imposing frescoes attributed to Pietro in the Lower Church at Assisi—Virgin and Child with St. Francis and scenes from the Passion.Ambrogio Lorenzetti, d. 1348?, was the more inventive brother. Also influenced by Giotto and Giovanni Pisano, he developed great simplicity of style and a remarkable ability to depict spatial depth. Several times he is recorded as having been in Florence. There he painted an altarpiece for the Church of San Procolo, which includes scenes from the life of St. Nicholas. His greatest achievement is the cycle of frescoes (1337–39) in the Palazzo Pubblico, Siena. It consists of allegories of good and bad government and is a revealing portrayal of Italian life in the 14th cent. The paintings are invaluable for their accuracy of depiction. Other works by Ambrogio are three frescoes depicting the Maestà in Siena, Presentation in the Temple (Uffizi), and Annunciation (Siena Pinacoteca). No records of the brothers appear after 1348; they are believed to have perished in the plague.

See study by G. Rowley (2 vol., 1958).