Carbon nanotubes, man-made molecular materials used widely today for various commercial and biomedical applications, have been hailed as the greatest innovation since the Industrial revolution. Multi-walled carbon nanotubes (MWCNT) are similar in structure to asbestos, a known human carcinogen that causes lung cancer and mesothelioma. However, there is limited information on the potential environmental and human health risks associated with exposure from either inhaling or handling these materials. In order to identify a risk assessment approach, MWCNT-induced gene expression changes in the whole genome were examined in the mouse lungs (n=160) exposed to 0, 10, 20, 40, or 80 g of MWCNT by pharyngeal aspiration at 1, 7, 28, and 56 days post-exposure.