Curiel de Duero is a municipality located in the province of Valladolid, Castile and León, Spain. It covers an area of 18,75 km², has a population of 134 inhabitants, yielding a density of 6,93 inhab/km². It belongs to the Valle del Cuco and the county (Spanish: Comarca) of Campo de Peñafiel. The municipalities of San Llorente, Corrales de Duero, Valdearcos de la Vega, and Bocos de Duero also belong to the Valle del Cuco. Roturas, that borders north to Curiel De Duero, historically also belonged to Curiel, but has in modern times not been included into the Valle del Cuco county.