The purpose of this study was to determine the difference between intercellular adhesion molecule-1 (ICAM-1) cytokine content in gingival crevicular fluid (GCF) on healthy periodontal and chronic periodontitis. It was also determine the treatment effects of hydrogen peroxide as subgingival irrigation in chroni periodontitis. Twenty participants were examined in this study. Gingival fluid collection method was carried out with strip paper technique and analyzed with enzyme-linked immunosorbent assay (ELISA). The result of the study showed that there was a significant change of ICAM-1 on healthy site and periodontitis site and there was a significant change of ICAM-1 content after treatment (p<0.05). We concluded that ICAM-1 in GCF is a sensitive indicator to differentiate healthy sites from those with periodontitis.