Saliva is a secretion of the salivary glands which ensures stability in the oral cavity environment. ¿Oral fluid¿ is composed of saliva itself, gingival crevicular fluids contained in the dentogingival sulcus, mucosal transudate, cell detritus, bacteria and food remains. Saliva can be collected with or without stimulation. Stimulated saliva is collected by masticatory action or by gustatory stimulation. Unstimulated saliva is collected without exogenous gustatory, masticatory or mechanical stimulation. Analysis of saliva may be useful for the diagnosis of hereditary disorders, autoimmune diseases, malignant and infectious diseases, endocrine diseases, evaluation of therapy efficacy for caries, periodontitis as well as in the assessment of therapeutic levels of drugs and monitoring of illicit drug use.