The target of this study was to evaluate the effect of extract of the European mistletoe - Viscum album quercus L. on spermatozoa motility and viability in vitro. The CASA system was used to determine the spermatozoa motility parameters at different time intervals (0, 1, 2 and 3 h) and spermatozoa viability was determined in five different doses of Viscum album quercus L [10 (QA), 6.6 (QB), 3.3 (QC), 2.5 (QD) and 2 (QE) mg/ml]. Results in experimental groups detected a significant deterioration on rabbit spermatozoa after 1, 2 and 3 hours, compared to the control. The initial total spermatozoa motility showed increased value for all doses of Viscum album quercus in comparison to control. After in vitro culture a dose-dependent decrease (QA: reduction of 69.7 %, QB: reduction of 40.9 %) was found. For the progressive spermatozoa most significant decrease (86.8 % for QA vs. 48.5 % for QB) was detected compared to the control after 3 hours of culture. Spermatozoa viability (MTT test) was decreased in all experiment groups at the end of experiment, but the differences were not significant. Significant alterations of membrane integrity were found in groups with the highest Viscum album quercus concentration (QA, QB), but acrosome integrity showed no significant changes. Results suggest negative dose- and time-dependent effect of Viscum album quercus at higher doses on spermatozoa motility and viability parameters in vitro .