| Montemarzino | |
| Official Name: | Comune di Montemarzino |
| Coordinates: | 44.85°N 9°W |
| Region: | Piedmont |
| Province: | Alessandria (AL) |
| Mayor: | Giammattia Nicolini Berutti |
| Area Total Km2: | 9.85 |
| Population Footnotes: | [1] |
| Population Total: | 309 |
| Population As Of: | 1 January 2021 |
| Population Demonym: | Montemarzinesi |
| Elevation M: | 448 |
| Postal Code: | 15050 |
| Area Code: | 0131 |
Montemarzino is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about 110km (70miles) east of Turin and about 30km (20miles) east of Alessandria.
Montemarzino borders the following municipalities: Avolasca, Casasco, Momperone, Monleale, Montegioco, Pozzol Groppo, and Volpedo.
Ancient imperial feud of the Oltrepò Pavese, in 1685 it was granted to the Spanish branch of the Spinola family, marquises of los Balbases, dukes of Severino and Sesto, lords of Casalnoceto, Rosano and Barisonzo. Governed with a feudal system by the marquises Paolo Vincenzo called Ambrogio (1685-99) and by Carlo Filippo Antonio (1699-1721), Ambrogio II Gaetano (1721-1724), in 1753 Gioacchino ceded the feudal state to the Savoys.