Saliva has been described as the mirror of the body as it reflects oral and systemic health. The presence of disease specific biomarkers in saliva, aid in identification and monitoring of the disease progress. As a result saliva has increasingly been evaluated for its use as a diagnostic medium in the detection of dental caries, periodontal disease and other infectious diseases, salivary gland diseases, systemic diseases such as cardiovascular, renal, autoimmune disorders and in malignancies. Saliva as a diagnostic tool offers distinctive advantages over other body fluids because of its non invasive collection method and others. With the evolution of modern technologies, the options for use of saliva in diagnosis is becoming extensive. This review highlights the application of saliva as a potential biological tool in health and in diagnosis and monitoring the progression of disease states.