Sienno [ˈɕɛnnɔ] is a town in Lipsko County, Masovian Voivodeship, in east-central Poland.

The history of Sienno dates back to at least the 14th century, in 1375 was built the first wooden church, at that time it belonged to the parish in Chotcza.

Between 1431 and 1442 Dobisław z Oleśnicy, the lord of Sienno, was built of a church of brick in the Gothic style and it was consecrated by Cardinal Zbigniew Oleśnicki.

Five Gothic paintings on Panel with from 1460 are located in Medieval Art Gallery in the National Museum in Warsaw.

Sienna residents participated in the January uprising and in the resistance during World War II.

Other Jews from the region were then briefly brought into the empty ghetto, later also to be gassed at Treblinka.

Sienno was the home town of prominent members of Dębno coat of arms including among others, Bishop of Krakow Cardinal Zbigniew Oleśnicki (later Archbishop of Gniezno), Jakub z Sienna.