In marine environment, actinobacteria are widely distributed in water and sediments, and form symbiotic relationships with higher organisms. In this study, we isolated 49 actinobacterial strains from three temperate stony corals , Pocillopora damicornis , Acropora hyacinthus and Acropora muricata . More than 60% of obtained actinobacterial isolates belonged to mycolic acid-containing genera, particularly members of the family Mycobacteriaceae . Our results combined with the previous studies demonstrated that these actinobacteria are frequently associated with coral hosts worldwide.