This study was undertaken to evaluate the validity of a new modified dip-slide test kit for the estimation of salivary mutans streptococci, lactobacilli and Candida levels by comparison with the results obtained from conventional agar plate counts. Five milliliters of paraffin-stimulated saliva sample was collected from 118 6-12-year old children attending 4 primary schools in Thailand. Saliva was poured over a 3-compartment slide containing Mitis-Salivarius Bacitracin agar, Rogosa agar and Sabouraud dextrose agar. A slide was incubated in a 5% CO2 incubator for 48 hours. The results of the modified test kit were compared with those from the conventional saliva sampling with dilution method. The salivary mutans streptococci, lactobacilli and Candida counts obtained from the conventional methods were significantly correlated (p < 0.0001) with the modified dip-slide estimates of these organisms. (Kendall Tau = 0.71, 0.58 and 0.76, respectively). The correlation between a modified dip-slide test kit and the conventional method indicates that this new test kit is suitable for the screening of salivary mutans streptococci, lactobacilli and Candida levels in patients. The test is simple and would be useful for the early selection of patients for dental examination. In addition, it would be a valuable educational aid for the motivation and dietary counseling among children.