The Balilla class were the first submarines to be built for the Italian navy following the end of World War I.

They were large ocean-going cruiser submarines designed to operate in the Indian Ocean based in Italy's East African colonies.

The design was double-hulled and based on the German Type UE II submarine U-boats, one of which, U-120 was supplied to the Italians as a war reparation.

During the war, the boats were stationed in the Mediterranean in 1940 but proved too large to be effective patrol submarines.

[1] The submarines were powered by two Fiat diesels for surface cruising and two Savigliano electric motors for use while submerged driving two shafts.

[1] The class was also armed with one 1924 model 120 mm (5 in)/27 calibre deck gun that was placed in a shielded mounting in the forward section of the conning tower.

Modifications to the standard Ballila design include the placement of the diesel and electric motors further forward, the elimination of the bow planes and a different distribution of the ballast tanks throughout the submarine.