Upto the present time, identification of the disease of caries has relied on the recognition of demineralization or cavitation on the tooth surface. Caries is a bacterial disease, and, therefore, the real beginning occurs with the introduction of a combination of specific bacterial population capable of surface demineralization, into an environment that has been modified to the extent that those particular species can flourish.Traditional observations of early detection have included visual, tactile and radiographic examination. These traditional methods are still in use in contemporary dental practices; however, some practices have been altered due to paradigm shifts or newer diagnostic technique.An attempt has been made through this dissertation to review the literature for the efficacy, predictability and reliability of the various diagnostic methods in detecting dental caries in order to preserve the tooth structure either by remineralization or by the least traumatic and theleast invasive technique.