Aim: To compare and evaluate the anti-cariogenic properties of the different plant extracts against various cariogenic micro-organism. Materials and Methods: In phase 1 the anticariogenic efficacy of 4 different herbal extracts namely ocimum sactum (Tulsi), Curcuma longa (Turmeric), Syzygium aromaticum (Laung) and Tinospora cordifolia (Giloy), will be evaluated against two strains of bacteria viz. S.mutans and L.acidophilus. In the second phase of the study, decay depth in tooth samples of 10 in each group will be compared within 4 groups using polarised light microscope. Results: The intragroup comparison for the different time intervals was done using Repeated Measures ANOVA to find the difference between the individual time intervals The level of the significance for the present study was fixed at 5% Conclusion: the anti-cariogenic efficacy of “Laung” (Syzygium acromaticum) was highest followed by “Tulsi” (Ocimum sanctum) than “Haldi” (Curcuma Longa) and “Giloy”. (Tinospora cordifolia) Giloy was found to be least effective among these against S. mutans and L. Acidophilus micro-organisms. The caries extension in dental tissue treated with different herbal extracts with aid of Stereo-light Microscope showed Giloy with higher caries incidence