Aim:To compare and evaluate the caries preventive efficacy of a resin infiltrant (ICON),Caseinphosphopeptide-Amorphous calcium phosphate (GC Tooth mousse) and Nanohydroxapatite(Aclaim) on non cavitated enamel lesions. Materials and methods: 60 maxillary incisors extracted for periodontal reasons were sectioned at the middle third region of the crown with approximate dimensions of (5x5x5mm). In order to create the artificial enamel lesions, the samples were demineralized by placing in a beaker containing the prepared demineralizing solution for 14 days. The samples were divided into four groups which is Resin infiltrant (Group I), CPP-ACP (Group II), nano-HA (Group III) and control (Group IV) (n= 15) enamel samples in each group. The caries preventive efficacy of each group was evaluated using Vickers microhardness tester and the results were statistically analyzed. Results: The mean microhardness value after demineralization of enamel samples was 226VHN, 222VHN, 207 VHN and 215VHN in Groups I, II, III, IV respectively. The mean microhardness value after Remineralization of enamel samples was Group I :316VHN > Group II : 282VHN > Group III : 267VHN > Group IV : 218 VHN. The mean microhardness after acid challenge of enamel samples for 14 days was 292VHN, 254VHN, 237VHN, 167 VHN in groups I,II,III, IV respectively. Conclusion: The resin infiltrant showed higher caries inhibition potential than CPP-ACP and nanohydroxyapatite. In addition, resin infiltrant showed superior acid resistance and increased surface microhardness compared to CPP-ACP and nanohydroxyapatite.