Documentary evidence of Pietro rather scarce, except those of biography, compiled by Giorgio Vasari. In connection with this reconstruction of his work and the Dating of most of the works are not accurate, but tentative. Pietro is traditionally considered a less creative and more conservative artist than his brother Ambrogio, and this is true, but only partly. Pietro Lorenzetti formed among the Mature work of Duccio, but in contrast to Duccio and Martini, his temperament was more dramatic and passionate. Pietro Lorenzetti has not abandoned the Sienese tradition, but made her slim aristocratic religious sounding a strong note of the human drama.
Pietro Lorenzetti, the elder brother master of the Siennese school of the XIV century Ambrogio Lorenzetti (died in 1348). Pietro was a contemporary of Simone Martini and, like him, in terms of creativity formed under the influence of «Byzantium» by Duccio di Buoninsegna, who studied painting. The earliest of the works, the authorship of which is well established, applies to 1320. This polyptych in the Church of Pieve di Santa Maria in Arezzo. At this time, Pietro Lorenzetti as well as Simone Martini, tried to refocus the direction of «Byzantium», perceived by Duccio di Buoninsegna, but Lorenzetti has used other artistic means of aesthetic and emotional expression. Influenced by the work of John. Pisano and Giotto Lorenzetti turned to an epic interpretation, he used the effects of colour, and the architectural background, which is built according to the laws of linear perspective. His work has taken a dramatic character, but Lorenzetti moved away from «golovskoy balance», reinforcing the note of tragedy in the created images and re-addressed to «Byzantium». «Birth of Mary» — a triptych, the work of a master in the heyday of his artistic personality, which, however, was interrupted by a sudden death during a plague epidemic. Other famous works: frescoes in the Lower Church of San Francesco in Assisi. 1325−1329 and after 1340.