In the recent years, the use of nanomaterials has increased exponentially. In spite of the extensive research in this field, some areas are not completely understood, one of them being nanosafety. Because of their size and shapes, these nanomaterials have the ability to be easily absorbed in the biological and the ecological systems and interfere with them by hampering smooth functioning. In this study, MTT Assay was used to evaluate the nanosafety of carbon based nanomaterials (Carbon Nanowire, Graphene and Carbon Nanotubes). All of the nanomaterials exhibited various levels of cytotoxicity. The level of cytotoxicity was dependent on the concentration, the size and shape of the nanomaterial. Smaller particle sizes exhibited higher cytotoxicities, which may be useful for the students, scientists, engineers and other participants who involve in these nanomaterials.