Aim: The aim of the present study is to assess and compare intraorally the effectiveness of 0.5% Camellia sinensis extract, 0.5% guava leafs extract, 0.2% sodium fluoride solution on the number of Streptococcus mutans and Lactobacilli spp. in the oral cavity. Materials and Methods: Forty four healthy children of age group 7–12 years was carried out. The subjects were randomly assigned to four groups: (A) 0.5% C. sinensis extract, (B) 0.5% guava leafs extract, (C) 0.2% sodium fluoride, and (D) Saline mouth wash as control group, with 11 subjects per group. Plaque samples were taken and streptococcus mutans bacteria was assessed. Salivary samples were taken and lactobacilli bacteria was assessed. The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 10ml of each solution per well. Results: In the in vitro analysis Fluoride, Green tea extract and Guava extract showed significant difference between the diameters of streptococcus mutans and lactobacilli bacterial inhibition zones at different concentrations. Conclusion: In this in vitro study, there was a strong positive significant correlation between the same variables of guava extract and fluoride, but there was no significant correlation between the diameter of streptococcus mutans bacterial inhibition zones and the concentration of green tea extract, while in lactobacilli there was a strong positive significant correlation between their concentration and the diameter of bacterial inhibition zones.