Oral health is essential. In the oral cavity, various kinds of bacterial colonies enter through food and drinks. One of the oral diseases is dental caries which is generally caused by the bacteria Streptococcus mutans and Staphylococcus aureus as normal flora which turns pathogenic due to predisposition. At the same time, mouth ulcer is caused by the fungus Candida albicans. One way to inhibit the growth of bacteria that cause dental caries and fungi that cause mouth ulcer is to rinse your mouth with saline solution. Salt has bactericide and bacteriostatic abilities due to its hygroscopic properties. The purpose of this study was to determine the antibacterial and antifungal activity of saline solutions against dental caries bacteria and the Candida albicans fungus in mouth ulcer. This study is an experimental study in the laboratory with 3 types of treatment and 2 controls, including K+ (povidone-iodine 1%), K- (mineral water), P1 (gargling 1 saline solution), P2 (gargling 2 saline solution), and P3 (gargling 3% saline solution) with 5 repetitions. Treatment for 3 days with respondents who had dental caries and mouth ulcer. Saliva collection is carried out before and after treatment. The saliva of respondents with dental caries was generated in BAP media, and the mouth ulcer was generated in PDA media. Data analysis using SPSS 16.0 Paired T-Test method with a significance level of 95%. The results showed that saline solution reduced the number of bacterial colonies in dental caries, with the treatment group that had the optimal outcome of reducing the number of bacteria in dental caries significantly was a concentration of 1% (p<0.05). Meanwhile, the saline solution has effect in reducing the number of colonies of the Candida albicans fungus in mouth ulcer, although insignificant (p> 0,05).