The aim of this study was to identify oral and cloacal aerobic flora of four-lined snakes (Elaphe quatuorlineata) from Croatian islands Cres and Olib to get better insight into bacteria and fungi potentially harmful to both the animals and the people getting in contact with those animals. Oral and cloacal swabs were taken from a total of 20 snakes and analyzed by standard microbiology and by Real-Time PCR method for Chlamydia spp. identification. Neither Salmonella spp. nor Chlamydia spp. were detected, but some potentially human pathogens, such as Aeromonas hydrophila, Escherichia coli, Serratia marcescens and Stenotrophomonas maltophilia, were isolated. Some of fungi detected, such as Candida albicans, Aspergillus flavus and Cladosporium sp., have already been described as secondary causative disease agents in reptile collections. To the author's knowledge this study is the first survey of aerobic microflora of four-lined snakes.