Saliva has emerged as a non-invasive, easily accessible biofluid for diagnostic purposes in dentistry and medicine. Biomarkers in saliva, such as proteins, enzymes, nucleic acids and metabolites, reflect both systemic and oral health. Advances in molecular science, nanotechnology and bioinformatics have enabled highly accurate assays for early disease detection, monitoring and treatment guidance. Salivary diagnostics are promising for identifying conditions like diabetes, HIV, COVID-19, autoimmune disorders, cardiovascular diseases and oral diseases such as periodontal disease and oral cancer. To fully realize its potential, regulatory approval, standardized procedures and further research on salivary biomarkers are essential.