Objective: To examine changes of four proinflammatory proteins in whole saliva in the early stage of plaque-induced experimental gingivitis. Methods: Eleven young male volunteers were recruited following the cessation of all oral hygiene measures for a period of 21 days. The levels of Interleukin-6 (IL-6), Interleukin-1ß (IL-1ß), calprotectin in saliva were determined with enzyme linked immunosorbent assay. The activity of elastase in saliva was examined. Results: IL-1ß, IL-6 and calprotectin in saliva increased gradually as plaque accumulated and peaked on the 14th and 21st day respectively. Moreover, the three proinflammatory proteins showed good correlations with clinical parameters, with IL-1ß correlating with clinical parameters more closely in particular. The activity of elastase in saliva elevated rapidly and peaked on the second day (P 0.01). However, after the seventh day, elastase activity declined slowly continuously. The change of IL-6 and IL-1ß in saliva showed a similar tendency throughout the experiment, the correlation coefficient was r = 0.687 (P 0.01), but there was no obvious correlation between calprotectin and elastase, even though both mainly come from neutrophils. Conclusion: Our study demonstrated that IL-6, IL-1ß and calprotectin concentrations in saliva could reflect the degree of gingival inflammation. The longitudinal change of elastase activity in saliva during the experimental gingivitis period was quite different from that of other pro-inflammatory proteins; reasons for the decrease of elastase activity in the late gingivitis period need further study. Keywords: saliva, interleukin-6, interleukin-1ß, calprotectin, elastase, experimental gingivitis