RANKL (receptor activator of nuclear factor kappa-β ligand) and OPG (osteoprotegerin) are two proteins involved in bone remodelling. During the active phase of periodontal disease, an imbalance between the ratios of the two elements can be noticed. While the expression of RANKL is elevated compared with that of OPG, the RANKL is available to bond with RANK (receptor activator of nuclear factor kappa-β). This study was conducted on 41 patients: 19 with generalized aggressive periodontitis, 18 with severe chronic periodontitis, and 4 periodontal healthy subjects. For each patient included, we determined the salivary levels of RANKL and OPG with the help of two Human ELISA kits. The results show that the patients affected by periodontitis, either aggressive or chronic, have significant higher values of RANKL and RANKL/OPG ratio. This values correlate with the local inflammation status.