Montalchez is a former municipality in the district of Boudry in the Canton of Neuchâtel in Switzerland . On 1 January 2018 the former municipalities of Bevaix , Saint-Aubin-Sauges , Gorgier , Vaumarcus , Montalchez and Fresens merged into the new municipality of La Grande-Béroche.

Montalchez is first mentioned in 1340 as villa de Montallichie.

Montalchez has an area, as of 2009, of 6.4 square kilometers (2.5 sq mi). Of this area, 3.72 km2 (1.44 sq mi) or 57.9% is used for agricultural purposes, while 2.41 km2 (0.93 sq mi) or 37.5% is forested. Of the rest of the land, 0.27 km2 (0.10 sq mi) or 4.2% is settled (buildings or roads) and 0.01 km2 (2.5 acres) or 0.2% is unproductive land.