Two types of carbon-based films, namely diamond-like carbon (DLC) and ultrananocrystalline diamond (UNCD) films were comparatively investigated. The DLC films were prepared by pulsed laser deposition (PLD) without or with additional ion bombardment, the UNCD films by microwave plasma enhanced chemical vapour deposition. The films were characterized with respect to their topography and morphology (AFM, SEM) and bonding structure, e.g. fractions of sp3 and sp2 carbon atoms (XPS, FTIR and Raman spectroscopy). Finally, the wettability and the surface energies of both types of films were investigated with contact angle measurements as well as the antibacterial properties with two types of bacteria.