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The purpose of study was to evaluate the anti-oxidant and anti-bacterial activities of three species of green, brown and red algae from northern coast of the Persian Gulf, The study was performed using DPPH, FRAP, PMD and RP tests for anti-oxidant capability and disk diffusion and plate methods of ethanol extraction for anti-bacterial ability. In the current investigation, The best anti-oxidant activity and inhibition potential of DPPH free radicals and RP were shown in ethanol extract of Entromorpha intestinalis green algae and lowest values was detected in Cystoseira myrica brown algae.The highest anti-oxidant activity was measured by FRAP test in green algae E. intestinalis and the lowest anti-oxidant activity was obtained in the red algaeGracilaria corticata.The highest anti-oxidant activity with PMD test was found in the red algae G. corticata. However, anti-oxidant activity of the green algae E. Intestinalis was shown high activity with DPPH, FRAP, RP tests. Hydro-alcohol extraction of sea weed did not show any anti-bacterial properties.