By reviewing all published and unpublished data, the present status of Nyctalus lasiopterus in Hungary was assessed. The species is known from 12 localities in the country, mostly situated in the North Hungarian Mountains. Only one stable population is known, which is located in the Mátra Mountains and has been present each summer since its discovery in 1995. Except for this population, the species is rarely found in other locations. Radio-tracking resulted in the finding of 13 roosting trees, which were exclusively beeches (Fagus sylvatica) in a montane beech forest. The largest roosting group consisted of more than 50 individuals. Sex ratio was highly female biased; adult males have rarely been found in the country. Lactating females and juveniles were captured regularly, which indicates the presence of a stable nursing population in the country. In Hungary, the main threat to N. lasiopterus is likely to be the logging of old beech forests. Further research is needed to draw a better picture of the Hungarian population of the species and strengthen the conservation of this magnificent bat.