The Martinengo Altarpiece is a painting by the Italian High Renaissance painter Lorenzo Lotto, finished in 1516.

On 15 May 1516, Lotto was in Bergamo to sign a contract for a large altarpiece for the high altar of the church of San Bartolomeo, funded by Alessandro Martinengo Colleoni, who had chosen the church as the family's new burial place (the outstanding Colleoni Chapel is located nearby).

The subject of the painting is a Holy Conversation, with the Virgin and the Child sitting on a throne surrounded by saints.

Some of the objects could be taken from Francesco Colonna's Hypnerotomachia Poliphili, alluding to the rule of Venice in Bergamo, of which Martinengo was a supporter.

There is a total of ten saints, including St. Alexander, eponymous of the donor, portrayed with a scintillating armor and, perhaps, with the face of Martinengo himself.