Periodontitis is defined as "an inflammatory disease of the supporting tissues of the teeth caused by specific microorganisms, resulting in progressive destruction of the periodontal ligament and alveolar bone with pocket formation, recession, or both." Diagnostic Marker can be defined as any biochemical compound such as antigen, antibody, abnormal enzyme, or hormone that is sufficiently altered in a disease to serve as an aid in diagnosis or in predicting susceptibility to the disease. Their findings serve as a basis for treatment planning and provide essential data during periodontal maintenance and disease-monitoring phases of treatment. Thus, we can say that biomarkers, whether produced by normal healthy individuals or by individuals affected by specific systemic diseases, are tell-tale molecules that provides pertinent information for differential diagnosis, localization of disease and severity of infection. Therefore, in this particular literature review, we aim to evaluate the potential diagnostic utility of various biological markers present in oral fluids, such as saliva and GCF and its potential application for the early diagnosis and treatment of periodontal diseases.