Objectives: The study aimed to investigate the relationships among salivary level of IgA, mutans streptococci and debris index (DI) of schoolchildren in Kanchanaburi province. Methods: This cross-sectional study was performed on schoolchildren, studying in four schools near Thai-Myanmar border. Stimulated saliva samples from schoolchildren were collected and analysed for total IgA in mg/ml saliva using ELISA technic. Salivary samples were also diluted and plated on MSB agar to determine the number of mutans streptococci using micromethod. The MS counts were transformed as log cfu/ml of saliva for the correlation analysis. Oral examination for DI was recorded by Greene and Vermillion method. Results: The total samples of 321 schoolchildren with 6-13 years of age were examined. Most of them (92.8%) had mutans streptococci in their saliva and 8.7% of schoolchildren had more than 106 cfu/ml saliva which was regarded as a high caries-risk group. 30.2%, 67.9%, and 1.9% of schoolchildren had good, fair, and poor levels of oral cleanliness (DI), respectively. The mean value of MS counts as log cfu/ml of saliva was 4.762. The mean of DI was 0.902 and that of total IgA was 0.316 mg/ ml of saliva. The Correlation analysis of salivary IgA, MS count and DI showed no statistical significant correlation (p>0.05). The analysis of differences in the amount of salivary IgA and MS counts among the three groups having different oral cleanliness (good fair and poor) statistically showed no significant differences (p>0.05). Conclusion: It was concluded that schoolchildren with different degree of oral cleanliness did not have statistically significant differences in the salivary levels of salivary IgA and mutans streptococci.