This work presents a study of corrosion resistance and cell viability of carbon films on bare and nitrided Ti-6Al-4V. Films deposited on bare alloy significantly improve the corrosion resistance. Unexpectedly, films deposited on nitrided alloy present delamination and cracking after 16 days. We associate, film failure with the presence of pores combined with a weak film/substrate interaction that allows diffusion of ions at the interface. We found that films tend to diminish the osteoblastic cell viability and the observed variations on film roughness do not improve cell viability. (C) 2014 Elsevier Ltd. All rights reserved.