Oral bacteria that degrade sulphur-containing amino acids (cysteine, cystine, and methionine) produce volatile sulphur compounds (VSCs = hydrogen sulphide, methyl mercaptan, and dimethyl sulphide) highly correlated with halitosis. When these bacteria are given the right environment, i.e. periodontal disease, cariogenic biofilm or food source they can grow in number very quickly and will start to convert proteins to VSC that, together with volatile fatty acids are largely responsible for oral malodor. Recently, the prevention of dental caries and periodontal diseases using various probiotics has been attempted. The purpose of this study was to investigate the effects of probiotics based on in vitro analysis, such as antibacterial activity, and to evaluate the neutralizing effect of probiotics on halitosis, the levels of VSCs were measured by gas chromatography. .