Over the few decades, lung cancer has appeared to be a global threat as globalisation improved worldwide. There are various risk factors which keep increasing, making the incidence and pathogenesis of lung cancer more complex. This study focuses on erythrina Indica lam. extract which has been believed to have various pharmaceutical effects based on their numerous phytochemical constituents. The aim of the study is to determine the antitumor activity of erythrina Indica lam. Leaf extract in human lung cancer cells. The effect of Erythrina Indica lam. From the cell viability experiment, the erythrina indica lam extract showed 50% cell growth inhibitory effect at 100μg/ ml (IC50) against the human lung cancer cells. Thus, there exists a significant antitumor activity of erythrina Indica lam. Extract, precisely at 100μg/ml, shows maximum potential inhibiting 50% of human lung cancer cells. Further studies should be done focusing the antitumor activity of the erythrina leaf extract, with any possibilities of side effects caused to make it as a natural alternative medication.