The chapel is dedicated to St. Andrea, depicted in the keystone.
The altar is dedicated to St. Abbondio.
The large engraved, gilded and painted wooden altar-piece is a masterpiece of the Lombard, Renaissance, by Giovan Antonio Del Maino from Pavia (c. 1515). .
Under the altar-table the altar frontal is the ancient one of the previous St. Abbondio altar (1490). It is a marble sculpture by Tommaso Rodari.
On either side of the altar-piece there are two large tempera paintings: on the left the Adoration of the Magi by Bernardino Luini , on the right the Flight into Egypt By Gaudenzio Ferrari from around 1520.
These canvases once closed the altar together with those of the same two authors arranged on the opposite span.
The bronze candlesticks are from the early 20th century by Ludovico Pogliaghi.
Under the northern organ, on the pillars behind the red marble columns, two reliefs by Rodari workshop face each other: the FIDES (towards east) , the SPES (towards west) ; two similar but by another artist reliefs with S. PROTO and S. GIACINTO are in high position under the organ ; in front of them under the other organ are the reliefs with the PACE and the CARITAS, while under the southern organ are two little devotional altars devoted to the saints LIBERATA and FAUSTINA, whose seventeenth century reliefs face each other.
The banner of the Confraternita del Ss. Sacramento, embroidered and painted, was designed by the painter Pier Francesco Mazzucchelli also known as Morazzone who painted the medallions (1608-1609). On the side towards the nave you can appreciate the figure of St. Abbondio surrounded by episodes of his life.