The present paper deals with bat mortality in Germany due to the action of wind turbines (up to now, 10 species in Germany and 15 in Europe) which is known at the present. According to the studies conducted in Brandenburg and Saxony it appears that most dead bats are found at the end of summer and during the autumn migration, a fact that is not statistically confirmed by the irregular checks carried out throughout the year and which should be considered only as an indication. About 93% of all the victims were found between the dispersal of the breeding colonies and the end of the autumn migration (August- September). 89% of the fatalities were around turbines whose towers were less than 100 m from wooded landscape features (woods and hedgerows). Because of the heterogeneity of the data, no difference in effect has been noted among the diverse types of wind turbines - all can be responsible for the death of bats. It appears obviously that the siting of the turbines has a direct influence on the number of bats killed. The possible reasons for this mortality are discussed here, but they are still largely unexplained and need more specific research. To this end a protocol for future comparative studies is presented.