The large frescoes illustrating episodes from the lives of the saints, which lend the room its name, are recognised by critics as a masterpiece by Pinturicchio, who produced the majority of them by his own hand.
The large lunettes host the figures of seven saints in an unusual iconographical order. St. Elizabeth, mother of John the Baptist, in the Visitation of Mary; St. Antonio Abbot and St. Paul of Thebes, hermits in the Egyptian desert, reunited in a single episode; St. Catherine of Alexandria in the Disputation; St. Barbara fleeing from the tower where she had been imprisoned by her father, who pursues her armed with a scimitar, because of her conversion to Christianity; St. Susanna, a biblical figure who rarely appears, forced to defend herself against two older suitors seeking to ensnare her and to jeopardise her absolute fidelity to her husband by spying on her as, unaware and unveiled, she bathed in her private garden, full of flowers and animals reproduced in minute detail; St. Sebastian, in the supreme act of his martyrdom, which according to tradition occurred on the Roman Palatine Hill, evoked by the Roman ruins of the Colosseum and the Church of Sts. John and Paul.
Above the door that leads to the adjoining Room of Mysteries there is a tondo with the Madonna and Child, in whose features Vasari identifies a portrait of the beautiful Giulia Farnese, beloved of Borgia, again by Pinturicchio.
Themes sacred to Christian culture and to profane cultures inspired by the myths of ancient Egypt or classical pagan culture are found in the very rich decoration of the room, deliberately centred on the presence of the bull, which continually recalls the heraldic emblem of Alexander VI, always referred to as “the ox” by both friends and detractors on account of his proud celebration of his family heritage.
It is not by chance that the subjects of the ceiling are based on the Egyptian myth of Isis and Osiris, assimilating the symbol of the Borgias with the ox, deified and worshipped by the Egyptians: Osiris, setting aside his royal vestments, teaches the Egyptians the use of the plough, the cultivation of vines and the harvesting of fruit; finally, he marries Isis, but is killed and mutilated by his wicked brother Set (Typhon) who spreads the parts of his body all over the earth. Isis manages to recompose the pieces of his body and to give them a solemn burial beneath a pyramid. Osiris reappears with the features of an ox, worshipped and carried triumphantly in procession by the Egyptians, who consider the ox Api as an image of the resurrected god.
Other episodes instead draw from Ovid’s Metamorphoses for the myth of the Greek princess Io, daughter of Inachus, King of Argos and beloved by Jupiter; he transforms her into a white heifer to hide her infidelity to Juno. Jupiter follows his beloved, and transforms her into a heifer to protect her from Juno’s wrath after being discovered by him; Juno, presuming the deception, asks for the heifer as a gift from Jupiter, who cannot deny him. She is entrusted to Argus Panoptes, with a hundred eyes; Mercury, sent as a messenger by Jupiter, kills Argus and frees the nymph, who is then however punished by Juno. This latter sends a gadfly to torment her, forcing her to wander endlessly until Jupiter intercedes and interrupts the torture. Io finally reaches Egypt, where she recovers her human features, becomes queen and is venerated by the people as the goddess Isis.