We assessed the levels of Interleukin-10 (IL-10), Interleukin-12 (IL-12), and Interleukin-18 (IL-18) in the gingival crevicular fluid (GCF) of subjects with advanced periodontitis (SIII-SIV) compared to healthy controls and evaluated their correlations with clinical measurements. The gene discussed is IL18; the disease is periodontitis.