This study, on the enological quality of rebollo (Quercus pyrenaica Willd.) has been done with three main points in mind; the requirement for quality wood for wine barrels; the large rebollo covered regions that can be found in Castilla-Leon (722.773 ha) as well as in other parts of Spain (1.090.716 ha); and the possibility of being able to give our wines their own personality, with recognizable characteristics. The study focuses on rebollo from Castilla-Leon, and addresses the chemical properties and structure of the wood, its evolution during the various stages of barrel-making, and its influence on the characteristics of wine aged in said barrels, in comparison to French and American woods, which are of well-known ecological quality.