Background and Objective: Dietary phytochemicals are known to exhibits anti-carcinogenic properties. This research investigated the inhibition of cellular proliferation and apoptosis induction by alpha-pinene (AP) against MDA-MB-231 human breast cancer cells. Materials and Methods: Cultured MDA-MB-231 cells were divided into four groups as follows: Group 1served as Control cells, Group 2, 3 and 4 served as AP treated groups in different concentrations of 05, 10 and 20 μM mL–1, respectively. After AP treatment, the cells were monitored and the morphological changes were examined after 24 hrs incubation. These cells were further used for various experiments. Results: MDA-MB-231 cells were given different concentrations (10-500 μM) of AP, which inhibited cell proliferation, increased ROS formation, altered mitochondrial membrane potential and caused apoptosis. Furthermore, real-time PCR analysis revealed that AP-treated cells had lower anti-apoptosis-related gene Bcl-2 and higher expression of the pro-apoptotic genes Bax, Caspase-3, -9 and cytochrome c. In addition, the protein levels of NF-κB, p-PI3K and p-AKT were downregulated in AP-treated cells. Conclusion: In conclusion, AP could suppress the cell viability, induce cell apoptosis via the apoptotic and inhibition of PI3K/AKT/ NF-κB signalling pathway in MDA-MB-231 cells.