In this study acetone was the best solution for extracting the effective antimicrobial materials from the algae species used in this experiment. A significant difference in antimicrobial activity was not found between the methanol and ethanol extracts of each alga. For instance acetone extracts of fresh Sargassum myricystum, Turbinaria conoides, Hypnea musiformis, Gracilaria edulis and Halimedia gracilis showed effective results against all test organisms, however the acetone extracts of Ulva lactua was low effective against micro organisms. This result could be related to the presence of bio active metabolites present in the Ulva, which are not soluble in acetone, but they can be soluble in methanol.