Background: Bisdemethoxycurcumin (BDMC) is a natural derivative of curcumin present in the phenolic components extracted from the dried rhizome of Curcuma longa L. BDMC demonstrated potential chemotherapeutic activities but the underlying mechanisms have not been fully clarified. In the present study, the role of reactive oxidative species (ROS) in the anti-cancer effects of BDMC was investigated. Methods: MCF-7 cells were exposed to BDMC, and then the cell proliferation, colony formation ability and cell cycle profile were analyzed. Cellular ROS level was determined by flow cytometry and fluorescent microscope observation using specific fluorescent probes. Mitochondrial membrane potential (ψm) was assessed using JC-1. In addition, effects of BDMC on senescence-related molecules were analyzed by western blot assay. Results: BDMC significantly inhibited MCF-7 breast cancer cell proliferation, while a rapid rise of the intracellular ROS level accompanied with a reduction of Δψm were observed. In addition, BDMC activated the pro-apoptotic protein p53 and its downstream effector p21 as well as the cell cycle regulatory proteins p16 and its downstream effector retinoblastoma protein (Rb). All of these BDMC-induced effects were counteracted with the pre-incubation of the antioxidant N-acetylcysteine (NAC). Conclusions: These results suggested that BDMC-induced ROS accumulation may contribute to its inhibitory effect on MCF-7 cell viability through regulation of p53/p21 and p16/Rb pathways. Copyright © 2013 by Institute of Pharmacology Polish Academy of Sciences.