Grengiols is a municipality in the district of Raron in the canton of Valais in Switzerland. The name of the municipality is first mentioned in 1052 as Graneirolis. Probably, the name was derived from the Latin word Graneirolas - meaning a small granary. Grengiols has an area of 58.5 square kilometers. Of this area, 22 % is used for agricultural purposes, while 26 % is forested. Of the rest of the land, 1 % is settled with buildings or roads and 52 % is considered as unproductive land. As of December 2020, Grengiols has a population of 431 inhabitants. 2.3% of the population are resident of foreign nationals.