Objectives: To study the oral health status, salivary mutans streptococci and dental treatment needs of schoolchildren in Kanchanaburi, Thailand. Methods: 695 schoolchildren of 5 primary schools, aged 6-15 years, were included in this descriptive cross-sectional study. The oral health examination was carried out following WHO criteria (1997). Stimulated saliva samples were collected to determine the number of mutans streptococci (cfu/ml. saliva) using MSB agar as selective medium and classified into four groups: negative, low, medium and high caries-risk groups. Results: The average age of schoolchildren in each of 5 schools ranged from 9.4-9.8years. While their average values of dmft, and DMFT ranged from 2.10-3.49 and 1.18-2.11, respectively. The percentage of schoolchidren having dental caries in the primary and permanent dentition in 5 schools were orderly 48.8% to 71.6% and 52.4% to 73.4%, respectively. Most of schoolchildren (83.9%) from five schools had microbiological caries-risk in medium levels (MS count 103-106cfu/ml saliva). 72.7% of all schoolchildren had fair levels (0.7-1.8) of oral cleanliness. The treatment needs of the total schoolchildren were filling restoration, extraction and endodontic treatment. Conclusions: This survey of 695 schoolchildren from 5 schools revealed the dental caries experience scores ranging from 2.10 to 3.49 in primary dentition and 1.18 to 2.11 in permanent dentition. Most of them had MS counts at medium level of caries-risk and fair level of oral cleanliness. The dental treatment needs were filling restorations, extractions and endodontic treatments. This study was supported by Mahidol University Research Grant.