The present study aimed to investigate the antibacterial properties of crude extracts from some soft coral species from the Red Sea, Hurghada, Egypt. Crude extracts of Lobophytum pauciliforum, Dendronephthya hemprichi, Sarcophyton
gracile, Sarcophyton glaucum, Sinularia gardineiri, Sinularia leptoclados, Nephthea pacifica, Sarcophyton acutum, Sarcophyton spongosium and Xenia macrospiculata, were tested against fish and human pathogenic bacteria. The well cut - diffusion technique was used to determine the absolute activity units (AU) and the minimal inhibitory concentrations (MICs) using disc-diffusion technique were determined against the most affected bacterial pathogens (E. coli and S. aureus). The AU of the ethanolic crude extract ranged from 1.4 to 25.0 for Sarcophyton acutum and
Lobophytum pauciliforum, respectively. On the other side, ethyl acetate crude extracts showed the highest AU (16.0) for L. pauciliforum against S. aeurus, followed by (11.1) of N. pacifica and X. macrospiculata against). The MIC of L. pauciliforum ethyl acetate crude extract was recorded as (50 mg ml-1) against both E. coli and S. areaus ATCC 6358.
Extracts from some soft corals showed the ability to inhibit the growth of some pathogenic bacteria indicating that it could be used for medical purposes.