Quantitative and qualitative studies concerning tumor necrosis factor α (TNF-α) and its receptors can prove essential for periodontal diseases diagnostics. Tumor necrosis factor is believed to be a very important mediator of inflammatory reactions and host immune response. Tumor necrosis factor α is the key cytokine of local inflammatory reaction within periodontal pocket, resulting from stimulation by bacterial factors. This cytokine initiates inflammatory process and activates mechanisms leading to periodontal tissue destruction. Another cytokine of interest in respect to periodontitis ethiopathogenesis is soluble TNF receptor I (sTNF RI). Observation of soluble TNF receptors as physiologic inhibitors of TNF led to its administration in therapeutic process as well as in therapy selected cases of aggressive periodontitis.