As a non–invasive and safe source, saliva could be a blood replacement in disease diagnosis and prognosis. Saliva can manifest from minor infections to malignancies. It is easy for both patients and clinicians to collect saliva. This article describes the latest advances in saliva–related studies and future benefits in early detection of oral diseases, such as dental caries and periodontal disease, as well as other systemic disorders including malignancy. Specific guidelines and outcomes regarding the future are expected. Salivary diagnostics should be available, along with high–sensitivity and various systemic and oral disease specificity tests.