| Montaldeo | |
| Official Name: | Comune di Montaldeo |
| Coordinates: | 44.65°N 61°W |
| Region: | Piedmont |
| Province: | Alessandria (AL) |
| Mayor: | Giovanni Maria Calcagno |
| Area Total Km2: | 5.38 |
| Population Footnotes: | [1] |
| Population Total: | 244 |
| Population As Of: | 30 November 2019 |
| Population Demonym: | Montaldeesi |
| Elevation M: | 332 |
| Postal Code: | 15060 |
| Area Code: | 0143 |
Montaldeo is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about 100km (100miles) southeast of Turin and about 35km (22miles) southeast of Alessandria.
Montaldeo borders the following municipalities: Casaleggio Boiro, Castelletto d'Orba, Lerma, Mornese, Parodi Ligure, and San Cristoforo.