Anti-cancer effects of a newly-synthesized palladium(II) complex, [Pd(sac)(terpy)](sac)center dot 4H(2)O (sac = saccharinate, and terpy = 2,2':6',2 ''-terpyridine), were tested against human breast cancer cell lines, MCF-7 and MDA-MB-231. The Pd complex had a strong anti-growth effect in a dose- and time-dependent manner in vitro. This effect was also confirmed by the experiment performed on Balb/c mice in vivo. The IC50 values were 0.09 mu M for MDA-MB-231 and 3.05 mu M for MCF-7. It was also very effective in disrupting the formation of MDA-MB-231 tubules on matrigel, indicative of a putative anti-invasive activity. It induced apoptosis via the cell death genes of DR4 and DR5. In conclusion, this newly-synthesized Pd (II) complex represents a potentially active novel drug for the breast cancer treatment. (C) 2011 Elsevier Masson SAS. All rights reserved.