Gold nanoparticles (Au NPs) are emerging as promising nanomaterials from which we construct diagnostic and therapeutic nanosystems. For understanding the fundamental behaviors of Au NPs with biological systems, interactions of Au NPs and cells should be considered¯rst. In this review, we present a detailed analysis of data on the cytotoxicity of most popular Au NPs including gold nanoclusters (Au NCs), spherical Au NPs, gold nanoshells (Au NSs) and gold nanorods (Au NRs). Relationships correlating the cell models, physicochemical properties (size, shape, chemical functionality and surface charge) of Au NPs and cytotoxicity are discussed on the basis of data analysis. Some general conclusions, current challenges and future prospects/solutions on the issue have been provided.