After Christ was taken captive at the Mount of Olives, Peter, fulfilling Christ's own prophecy, denied him three times before the cock crowed. His bitter repentance for this is the essential subject of this painting. The subject of Peter repentant is typical for the Counter-Reformation that started at the end of the 16th century. Whereas the worship of Peter (as of all the saints) was rejected by the Protestants, among Catholics he nevertheless enjoyed especial reverence as the founder of the Church and the first Pope. The motif of his tearful repentance was used for devotion and meditation for those in doubt and became a symbol of increased faith.

The saint is shown half-length, eyes full of tears raised to Heaven; he wrings his hands, folded as if for prayer. The white, shining ring of clouds in the stormy sky forms a kind of halo around his white head. The compositional scheme for the St Peter in Tears was taken by El Greco from his two Penitent Magdalens (in Budapest (1576-1577) and in Kansas City (1580-1586)). It is practically identical with the latter, in particular.