Background and AIM: Mouthwashes are one of methods used to reduce decay. Fluorin total mouthwash is a new mouthwash, so far no research has been done on its effect on streptococcus mutans. Materials and Methods: Research was done on 20 samples in two groups and 1 control sample. In this study, the diameter of growth inhibition zone for streptococcus mutans bacteria was compared between fluorin total and chlorhexidine mouthwash.the bacteria were cultivated on 21 blood agar plates.Each disc of chlorhexidine and fluorin total was placed on a plate.10 plates contain chlorhexidine disk and 10 plates contain flourin Total disk. Also antibiogram disk and a blank disk without mouthwash were put on 1 plate. The plates were placed at 37° C for 24 to 48 hours into the incubator and then the growth inhibition zone was measured and t-test was performed. Results: The growth inhibition zone in the chlorhexidine and fluorin total group was 15.4±0.5 mm and 11.4±0.5 mm, respectively, which was 4mm higher in the chlorhexidine group,which is statistically significant.(P˂0/0001) Conclusion: chlorhexidine mouthwash is more effective than Fluorin total mouthwash on streptococcus mutans.