Pietro Lorenzetti (c. 1280 – 1348) or Pietro Laurati was an Italian painter, active between c. 1306 and 1345. Together with his younger brother Ambrogio, he introduced naturalism into Sienese art. In their artistry and experiments with three-dimensional and spatial arrangements, the brothers foreshadowed the art of the Renaissance.

Lorenzetti’s last major work (1342) was a triptych altarpiece, the Birth of the Virgin, commissioned for Siena Cathedral. This painting in tempera on panel, like many Sienese paintings of the time, celebrates the life of the Virgin, the city’s patron saint.