ABSTRACT Present study aim to evaluate the antimicrobial, antioxidant and cytotoxic potential of crude extract of Marine Streptomyces carpaticus MK-01 isolated from seawater collected from Daejeong-cost of Jeju Island. About 24 actinomycetes strains were isolated and subjected to morphological and molecular analysis that confirmed the isolate as S. carpaticus MK-01. Crude ethyl acetate extract of MK-01 strain showed extensive antibacterial activity against Gram-positive fish pathogenic bacteria namely Streptococcus iniae and S. parauberis with a maximum zone of inhibition (0.92±0.03mm) was recorded against S. parauberis at the minimum extract concentration (3.12µg/ml). The MK-01 ethyl acetate extract shows dose dependant significant increase in antioxidant activity. The 50% cytotoxic concentration (CC50) of MK-01 ethyl acetate extract was attained at 53.71 μg/ml and the effective concentration 50 (EC50) against virus-infected Epithelioma papulosum cyprini cell lines was 8.72 μg/ml of S. carpaticus MK-01 crude ethyl acetate extract.