Abstract: Abstract: Objective To study the effect of endogenous Farnesol by Candida albicans on enamel demineralization of Streptococcus mutans. Methods The sections of human enamel were divided into 5 groups. The first three groups were exposed to Streptococcus mutans suspension mixed with deionized water, liquid supernatant of Candida albicans for 24h at 37℃, and Candida albicans suspension. The fourth group was totally exposed to Candida albicans suspension as the experimental group, while the deionized water was used in control group under the same conditions．Enamel demineralization was evaluated by the amount of calcium in the liquid medium at 24,48,72h using atomic absorption spectrophotometry. Results The concentrations of calcium in groups with liquid supernatant of Candida albicans for 24h at 24,48,72h were respectively （80.26±1.63）、（81.14±1.24）、（78.31±0.76）μg/ml, which were obviously lower than other groups .There was significant difference between the experimental group and the control group (P<0.05). Conclusions The results show that endogenous Farnesol by Candida albicans has apparent effect on inhibiting enamel demineralization induced by Streptococcus mutans.