In Eastern Europe, wind energy production is currently promoted as an important source of renewable energy, yet in most cases without appropriate consideration of the negative impacts wind turbines (WT) may have on protected species such as bats. Here, we present first data on fatality rates, fatality factors and the likely origin of bats killed by WT in the Dobrogea region (Romania), located in a major migratory corridor for wildlife in Eastern Europe. Over a 4-year period, we found a total of 166 bat carcasses from 10 species, mostly representing migratory species such as Pipistrellus nathusii and Nyctalus noctula. Most fatalities at WT occurred in July and August. We documented 15 cases of barotrauma and 34 cases of blunt-force trauma in carcasses found below WT. After adjusting for carcass removals and variations in searcher efficiency, we estimated for the 4-year study period a total of 2394 bat casualties at the studied WT facility consisting of 20 units, resulting in a mean fatality rate of 30 bats/WT/year, or 14.2 bats/MW/year. By implementing a curtailment measure at wind speeds below 6.5 m/s, we reduced fatality rates by 78%. Isoscape origin models based on hydrogen stable isotope ratios in fur keratin revealed that the majority of N. noctula that were killed by WT or captured nearby in mist nets originated from distant areas in the North (Ukraine, Belarus, Russia). The estimated high fatalitjegangy rates of bats at WT in this area have far-reaching consequences, particularly for populations of migratory bats, if no appropriate mitigation schemes are practised.