Objectives : This study was carried out to examine the effect of varnish fluoride and APF gel on the acid resistance and the remineralization of the enamel. Methods : At first, the microhardness changes of enamel surface were measured after demineralizing the fluoride treated tooth surface. Next, the changes were measured after fluoride application to the demineralized enamel surface. Results : 1. Acid resistance was higher in varnish fluoride groups than APF gel groups and the difference was significant(p<0.001). 1) Varnish fluoride groups Microhardness of enamel surface showed $297.76{pm}9.89$ after fluoride treatment and $260.90{pm}28.67$ after drmineralization. The changes of Vickers hardness number(VHN) were $-36.86{pm}27.30$. 2) APF gel groups Microhardness of enamel surface showed $298.79{pm}17.28$ after fluoride treatment and $43.75{pm}18.58$ after demineralization The changes of VHN were $-255.04{pm}21.31$. 2. No significant changes were surveyed in both varnish fluoride groups and APF gel groups as for remineralization of enamel(p>0.05). 1) Varnish fluoride groups Microhardness of enamel surface showed $46.58{pm}15.42$ after demineralization and $46.61{pm}15.70$ after fluoride treatment. The changes of VHN were $0.02{pm}3.75$. 2) APF gel groups Microhardness of enamel surface showed $47.13{pm}19.31$ after demineralization and $42.59{pm}16.12$ after fluoride treatment. The changes of VHN were $-4.54{pm}5.06$. Conclusions : Varnish fluoride showed higher acid resistance than APF gel, however both of them were observed to have no effect on the remineralization of the enamel.