Objective: The present study was aimed to investigate the effects of alcoholic root extract of Ocimum sanctum, in human non-small cell lung carcinoma cell (NCI-H460). Methods: The effect of ethanolic extract of O. sanctum in NCI-H460 cell was investigated by the cell viability assay, generation of ROS in a cancer cell, apoptotic morphological changes and by mitochondrial membrane potential. Results: The cytotoxicity was observed by MMT assay. NCI-H460 cell was treated with various concentrations (10-150 μg/ml) of extract for 24 hr and 150 μg/ml showed a maximum decrease in cell viability. The extract (25-100μg/ml) showed significant increase ROS production in NCI-H460 cell. It greatly inhibits cell viability and colony forming capacity of NCI-H460 cell, possibly because of increased oxidative stress. An increased apoptotic cell in Ocimum sanctum further shows its anticancer nature. Loss of mitochondrial membrane potential is an early stage of apoptosis. Our results showed that extract treatment caused serve loss of in NCI-H460 cell. Conclusion: The present study suggests that O. sanctum extract act by increasing oxidative damage in NCI-H460 cells. © 2017 Elsevier B.V., All rights reserved.