Introduction: Siwak (Salvadora persica), an oral cleansing tool which came from ancient Arab has Islamic cultural values. Many researches concluded that siwak contains antibacterial agent which has function to kill bacteria causing oral malodor (halitosis). Objective: The purpose of this study was to analyze halitosis parameters change which consisted of Volatile Sulfur Compounds (VSC), Bleeding on Probing (BOP) and tongue coating after using siwak at 11-13 year old students in Tapak Sunan Boarding School. Materials and methods: This study used experimental research method and 25 students in the age group of 11-13 year old became subjects of this study. Halitosis parameters measurements were taken before and after using 10 days siwak usage and through dental health education. OralChroma and organoleptic score were used to measure the VSC. Probing on six sites of gingival sulculs of each tooth was used to measured BOP. Classification of tounge coating was performed by observing the presence of white coating on the tongue surface. Statistical analysis was performed using Paired-t Test with p<0.05 as the level of significance. Results: Approximately 75% reduction of total VSC concentration was observed after siwak usage. Number of subjects with score 1 in organoleptic assessment for halitosis was also increased by 36%. Followed by reduction of BOP and tongue coating score by 57.7% and 26% respectively. Statistical analysis of those parameters showed significant differences before and after siwak usage. Conclusion: Siwak usage sucessfully decreased all halitosis parameters of the 11-13 years old students in Tapak Sunan Boarding School.