Objectives : This study was carried out to investigate the inhibitive effects of cotton plant sectional extracts in cancer cell lines, Calu-6(human, Caucasian, lung, adenocarcinoma) and MCF-7(human, Caucasian, breast, adenocarcinoma). The incidence of cancer has been increasing even in korea due to the change of dietary life and westernization and becoming conspicuous as the disease threatening health. But cancer treatment have not been fully effective against the high incidence or low survival rate of most cancer. Methods : Calu-6 and MCF-7 cells were cultured and seeded in cell culture plates, respectively. And sectional extracts of cotton plant were treated to MCF-7 cells. Results and Conclusion : Sectional extracts of cotton plant showed no anti-proliferative effect on MCF-7 cells, but root and stem extracts showed strong anti-proliferative effects on Calu-6 cells. Fruit, leaf and flower extracts also showed anti-proliferative effects on Calu-6 cells but not so much like root and stem extracts. But seed extract showed no anti-proliferative effect on Calu-6 cells.