The photocatalytic cytotoxicity of metallic gold-capped TiO2 (Au@TiO2) colloidal nanopellets was investigated against HeLa cells under UV-vis light irradiation. The morphological structure and the surface species of Au@TiO2 nanopellets were determined by using UV-vis absorption spectroscopy, TEM, SEM, XPS, XRD, and EDX techniques. The photocatalytic cytotoxicity of Au@TiO2 nanopellets was compared with that of TiO2 alone under the same experimental conditions. The cytotoxic effect of Au@TiO2 nanopellets was found to be 100%, whereas that of commercial TiO2 (P25) was ca. 50%.