This study aimed to remineralization of demineralized human enamel surface by using casein phosphopeptide amorphous calcium phosphate paste (Tooth Mousse) and compared it with acidulated fluoride gel in an in vitro study. Thirty extracted premolars randomly divided into three groups tooth mousse group, fluoride gel group and control group. All groups were subjected to demineralization process. A vicker hardness number was done for a baseline measurement. The all groups were subjected to 20 days pH cycling model and Vicker Hardness Number was retaken to compare it with the initial measurement. The mean surface enamel microhardness in the three groups ranged from 337.8 ±30.5 in the tooth mousse group to 360 ±42.9 in the fluoride group when measured after initial demineralization. In tooth mousse group, there was a statistically significant increase in mean microhardness after pH cycling. Conclusions. Tooth mousse increase resistance of demineralized of enamel surface.