Propolis has a long history of use in traditional medicine dating back to at least 300 BC, and has been reported to have a broad spectrum of biological activities. Since most studies have to date focused on medical uses of propolis, its antimicrobial activity against honey bee diseases has been little studied. One of the aims of this study was therefore to investigate the potential use of propolis in honey bee health, especially against American foulbrood, which causes much damage in the beekeeping industry. The second aim was to reveal the different antimicrobial activities of propolis collected from different geographical areas from the neighbouring countries of Greece and Turkey. Propolis samples collected from several regions of Greece and Turkey were investigated for their in vitro antimicrobial activities against Paenibacillus larvae. Eighteen ethanol extracts of propolis (EEP), (nine from Greece and nine from Turkey) were tested for antimicrobial activities against ten P. larvae isolates. The results showed that all P. larvae strains were susceptible to propolis extracts from both Greece and Turkey Furthermore 50 % concentrations of EEP caused significantdy wider inhibition zones (P <= 0.05) around the discs. Comparisons of the content, and locations and botanical origins of EEPs from Greece and Turkey showed that the kind of vegetation is more important factor than geographic location for their antimicrobial activity. This is the first comprehensive study concerning the antimicrobial activity of propolis samples collected from a wide area around the Aegean Sea.