Screening of compound with potent biological activity from natural sources is need of the hour. Many pharmaceutical companies are focusing on the seaweeds to isolate potent compounds. The present study also focuses on screening the In-vitro antioxidant and cytotoxic activity of see weeds Haloplegma duperreyi montagne and Halymenia dilatata zanadarini. In this study we used methanolic extracts of seaweeds. Methanolic extraction process was carried out using Soxhlet apparatus. The preliminary phytochemical screening was done. In-vitro antioxidant activity was studied using DPPH and ABTS radical scavenging activity. Cytotoxicity against lung cancer cell line was studied using A549 cell line. Both the extract showed best antioxidant activity and cytotoxic activity against A549 cell line. Extract 1 showed 56.16% cell death and extract 2 showed 62.08% of cell death. Both the sea weeds showed cytotoxic activity against lung cancer cell line A549. Further studies have to be carried out to find the mechanism of the cytotoxic activity.