OBJECTIVE:The present study was to investigate the anti-acidic etching effect of a kind of toothpaste containing biotin-polypeptide. METHODS:28 enamel slabs were treated with polypeptide-containing toothpaste in the pH-cycle environment,and then were analyzed by micro-hardness detector and polarized light microscope.RESULTS:The dental enamel treated with polypeptide-containing toothpaste was harder than the control group (P<0.0001);and the degree of demineralization in treated group was also less than the control one.CONCLUSION:There was certain acid resistant effect using the polypeptide containing toothpaste to treat the dental enamel.