The current study investigated an endogenous mycobiota of grapes in Eastern wine region, Slovakia and detection a potentially pathogenic isolates to produce selected mycotoxins. Intact berries from four wine grape cultivars were tested. Seven/eight berries superficially sterilized from each samples were placed on a Dichloran Rose Bengal Chloramphenicol agar in a total of 50 and incubated at 25 °C, 5 - 7 days. A total of 582 isolates were obtained that belonged to ten genera: Alternaria, Aspergillus, Botrytis, Cladosporium, Epicoccum, Fusarium, Mucor, Penicillium, Rhizopus, Trichoderma and one unidentified genus Mycelium sterillium without creation fruiting bodies. The most frequent were genera Alternaria, Aspergillus, Botrytis and Penicillium with 100 % frequention. The most frequent Aspergillus species was Aspergillus section Nigri (100 %) and Penicillium species was Penicillium chrysogenum (50 %). The largest number of isolates belonged to Alternaria (275 isolates), Cladosporium (114 isolates) and Penicillium (92 isolates). For that reason the relative density of both genera were the highest 42 %, 19.6 % and 15.8 %, respectively. The selected isolates – Aspergillus flavus, Aspergillus section Nigri, Penicillium citrinum, Penicillium expansum and Penicillium chrysogenum were tested for patulin, citrinin, penitrem A, roquefortin C, ochratoxin A, aflatoxin B1, G1 and cyclopiazonic acid producing ability. Out of 11 strains 54 % produced at least one mycotoxin. In our research ochratoxigenic microfungi (some species of Aspergillus section Nigri) were found in grape samples but without production of OTA.