In vitro antioxidant activities of extract from 41 marine algae species (05 Clorophyta, 29 phaephyta and 07 Rodophyta) from the coast of central of Vietnam were evaluated using different biochemical methods: reducing activity, DPPH scavenging activity and total antioxidant. All tested samples display antioxidant activity to various degree. Of the tested seaweeds, the extract of three species (Prionitis ramossissima, S.polycystum, S.crasifolium) demonstrated great antioxidant potential with very high scavenging activity Sc (100 percent, 91,7 percent
97,07 percent
respectively), at the concentration of 1,5 mg extract. while extract from Dictyota dichotoma was found to be highest total antioxidant activity (19,6mg ascorbic acid equivalent/g seaweed) and extractfrom S.microcystum exhibited highest reducing activity (23,1 mg Fi+ equivalent/g seaweed). These results suggest that some microalgaes from the coast of Vietnam have a great antioxidant potential which could be considered for future applications in medicin, food production or cosmetic industry.