10.22376/ijpbs.2019.10.1.p1-12 Volume 12 issue 4 October - December Halitosis (bad breath) describes the foul and repulsive odours detected in the breath of people. Oral commensal probiotic lessThan i greaterThan Streptococcus salivarius lessThan /i greaterThan K12 (BLIS K12 lessThan sup greaterThan TM lessThan /sup greaterThan ) has been recognised to offer potential benefit in oral health. This is due to its ability to colonise the oral cavity and ward off pathogens implicated causing oral and dental ailment such as halitosis. The aim of this systematic review was to search and analyse 1) the published literature on orally targeted lessThan i greaterThan S. salivarius lessThan /i greaterThan probiotic strain K12 and 2) its effects in conjunction with oral hygiene measures in reduction of halitosis. The research questions were formulated according to the PICO strategy. A broad search for published articles was conducted using the electronic databases such MEDLINE through PubMed, SciFinder and Web of Science by two independent reviewers. The quality of the studies was assessed using the JADAD scale and the risk of bias was assessed according to the Cochrane Collaboration assessment tool. A total of 335 articles related to lessThan i greaterThan S. salivarius lessThan /i greaterThan K12 were identified. Of these articles, after manually filtering out duplicates, 157 articles were identified as unique. All unique articles were screened on their titles and abstracts and another 154 were excluded. The full text of the remaining 3 articles were reviewed with relevance to halitosis were included in this review. The overall risk of bias of the selected trials was found to be of low risk. Studies with lessThan i greaterThan S. salivarius lessThan /i greaterThan K12 demonstrated a significant reduction in halitosis parameters in conjunction with routine oral hygiene practices, especially when the application of the probiotic was combined with a pre-treatment of a strong mouthwash. Marte Eva Koelemaij, John David Francis Hale, and Rohit Jain Halitosis bad breath, oral health, probiotics, Streptococcus salivarius K12, BLIS K12TM 27-34