Is the occurrence of Viscum album (European mistletoe) related to calcareous soils? – The aim of this study was to find an explanation for the occurrence of Viscum album L. outside the regions with calcium-rich soils in the province of Limburg (Belgium). Particular attention was paid to the concentrations of calcium in the soils below the trees and in the leaves of mistletoe and its host plants. Literature suggests that mistletoe prefers calcareous soils. The species also occurs in the Campine region where the calcium levels in the mainly sandy soils are low. Our analyses show that where mistletoe occurs the host always contains sufficiently high concentrations of calcium, regardless of the calcium concentration in the soil. The question remains why mistletoe has been reported only since the year 2000 outside the regions with high soil calcium contents. An extension of the distribution area of mistletoe was also observed in the provinces of Flemish Brabant and East and West Flanders.