Neofabraea is a genus of an important plant pathogenic fungi having worldwide appearance. Four Neofabraea species are responsible for bull's eye rot of pome fruits. The aim of this thesis was to investigate which of these species occur in the Czech Republic. 81 isolates were collected during a two- year period and they were identified using PCR fingerprinting (primers ERIC 1R and M13-core) and DNA sequencing (ITS, mtSSU and tub2). The results showed that species N. alba, N. perennans and Cryptosporiopsis kienholzii occur in the Czech Republic. According to available information, this is the second record of C. kienholzii in Europe. One isolate (KP4) failed to be identified as any of the species. KP4 is very close to C. kienholzii, but it can be distinguished both biologically and genetically. Furthermore, the aggressiveness of individual species was compared.N. perennans and strain KP4 proved to be most aggressive, the least aggressive is C. kienholzii. Two N. alba strains (KP36 and KP37) isolated from healthy apple fruit and leaf are pathogenic for apple fruits. Keywords: aggressiveness, Cryptosporiopsis kienholzii, Dermateaceae, Helotiales, apple tree, Malus, PCR fingerprinting, postharvest diseases Powered by TCPDF (www.tcpdf.org)