The aim of this study was to isolate and identify endophytic bacteria from stems of Chelidonium majus L. (greater celandine) and to evaluate their antifungal properties. In total, 34 bacterial endophyte strains were isolated. The fungistatic effects of these bacteria on the growth of five moulds (Alternaria alternata, Chaetonium sp., Paecilomyces variotti, Byssochlamys fulva, Aureobasidium pullulans) and one species of black yeast (Exophiala mesophila) were tested. The majority of the bacterial isolates were found to inhibit the growth of fungi and those with the strongest antifungal properties were further characterized. Of the twelve isolates examined, 11 were species of Bacillus thuringiensis and one was Bacillus amyloliquefaciens.