The article presents the important unpublished 'Dead Christ' by Francesco di Giorgio in the basilica of Santa Maria dei Servi in Siena. Modelled in terracotta and painted, this masterpiece of the Sienese Renaissance was discovered in 2009 and restored between 2015 and 2017. It is a late work by the artist, comparable to sculptures he executed in Siena around 1490. It is particularly reminiscent of the two bronze 'Angels' from the main altar of the duomo in Siena, the 'Saint Christopher' of the Louvre in Paris and the terracotta fragment with a 'Saint Anthony Abbot' of the Museo dell'Opera del Duomo in Siena. The paper also presents some unpublished documents concerning relations maintained by the friars of Santa Maria dei Servi in Siena with such masters as Lorenzo di Mariano, Michele di Ciolo Cioli, Ventura di ser Giuliano di Tura, Bartolomeo Neroni and Domenico Beccafumi.