Syringodium isoetifolium belongs to the family of Cymodoceaceae and found throughout India. The present study has been carried out to evaluate the preliminary phytochemical screening and antioxidant activity of the ethyl acetate extract of Syringodium isoetifolium. The present investigation is to evaluate the antioxidant activities of ethyl acetate extract of whole plant of S. isoetifolium in different invitro methods. The antioxidant activity was evaluated by using DPPH scavenging assay, reducing power assay, Nitric oxide (NO) scavenging assay and ABTS cation decolorization assay. Further the study continued with the anticancer activity by MTT Assay. The viability of the cell decreases with the increasing concentration of the drug. So, the invitro study clearly indicates that S. isoetifolium has a strong antioxidant activity. This study revealed that ethyl acetate extract of whole plant of S. isoetifolium comprise effective potential source of natural antioxidant