Viscum album L. is a medicinal plants used for many years as a remedy in the traditional medicine and in complementary cancer therapies. We investigated the influence of some host trees (Acer campestre, Fraxinus excelsior, Populus nigra, Mallus domestica, and Robinia pseudoacacia) and the seasons (May, July and December) on antioxidant activity of European mistletoe (V. album) using four different methods: (DPPH, ORAC, TEAC and Folin-Ciocalteu). Also, the influence of solvent (water and ethanol) was investigated. In general, antioxidant activity of mistletoe determined by DPPH and ORAC assay recorded the highest activity in the ethanolic extract, while the antioxidant activity of mistletoe extracts determined by TEAC and Folin-Ciocalteu assay recorded the highest activity in the aqueous extract. The promising mistletoe extracts recording with DPPH assay are VAF, hosted by Fraxinus excelsior followed by VAR, hosted by R. pseudoacacia (77.19% respectively, 76.6% DPPH scavenging effect). The values obtained from ORAC assay, in three different months (May, July and December), did not differ significantly, between all the ethanolic mistletoe extract investigated. The mistletoe hosted by R. pseudoacacia (VAR) has the highest level of scavenging cation-radicals ABTS *+ (1.7 ± 0.04 mM Trolox equivalents/g fresh matter). The values obtained for total phenolics in aqueous mistletoe extracts, harvesting in December decreased in the order: VAM (134.18 ± 0.01 mg GAE/ g fresh matter > VAF (122.08 ± mg GAE/ g fresh matter) > VAR (114.57 ± 0.004 mg GAE/ g fresh matter). The differences in the antioxidant activity between the leaves and stems of mistletoes harvested from different trees, and different seasons, can be attributed to environmental factors such as climate and temperature which can significantly affect the accumulation of the antioxidant components in the plant tissue.