Aims and Objectives: Mouthwashes with antibacterial activity inhibit the growth of bacteria in the mouth and teeth. Chlorhexidine is one of the most widely used mouthwashes that inhibits dental plaque and prevents tooth surface decay. Recently, concerns have been raised that alcohol-containing mouthwashes may have carcinogenic properties and may be harmful to children and pregnant and lactating women. The aim of this study was to determine the antibacterial effects of chlorhexidine mouthwashes with and without alcohol on common oral bacteria. Material and Methods: In this in vitro study, bacterial species were purchased from a research center and were cultured separately in proprietary environments in test tubes. Thereafter, mouthwashes with alcohol, without alcohol, and with salt water (saline) were added to test tubes containing the bacteria grown. The samples were then analyzed using a spectrophotometer to determine viability, growth rate, and bacteria waste. Finally, the data were analyzed using SPSS version 17 through analysis of variance (ANOVA) and Tukey statistical tests. Results: The obtained results showed that the saline group had the highest antibacterial activity and that the average antibacterial activity of the alcohol and alcohol-free groups did not differ significantly (P > 0.05). Post hoc test results showed that the antibacterial activity of the saline group was significantly different statistically from that of the other two groups. Conclusion: On the basis of the results, it can be concluded that both alcohol-free chlorhexidine and alcohol-containing chlorhexidine are effective in removing oral microbes. Moreover, by using alcohol-free chlorhexidine, the harmful effects of alcohol can be prevented.