Collegiata di San Martino, Renaissance collegiate church in Sinalunga, Italy.

The Collegiata di San Martino is a church with a single nave, Latin cross layout, eight side chapels, and a barrel vault. This vault spans the transept and main space.

This church was built in 1588 and used stones from the destroyed castle of Sinalunga. That fortress had been torn down after Florence's victory over Siena in 1559.

The church's name comes from the old church of San Martino, later called Santa Croce, from which several altarpieces were moved here. The Compagnia di San Rocco, founded in 1540, kept its own altar, built in 1613–1614 to a design by Antonio da Montepulciano, where a Sodoma painting was placed in 1614.

The church stands in the centre of Sinalunga, in the province of Siena, within the Diocese of Montepulciano-Chiusi-Pienza. It is an active place of worship, so visits should be timed around services. The facade is reached by a flight of steps, and the nave is lit only by the two windows of the counter-facade.

The church preserves a wooden crucifix from the 16th century by an unknown sculptor. Along with an Annunciation by Agostino Veracini, it shows the artistic range of the collection.