Objectives: To evaluate the validity of a modified dip-slide test kit for estimation of salivary mutans streptococci, lactobacilli and Candida levels by comparison with results obtained from conventional agar plate counts. Methods: 5 ml of paraffin-stimulated saliva sample was collected from 95 children 6-12-yr 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 CO2 incubator for 48 h. Results of the modified dip-slide test were compared with those from conventional saliva sampling with dilution method. Results: The salivary mutans streptococci, lactobacilli and Candida counts obtained from conventional methods were significantly correlated (p< 0.0001) with the modified dip-slide estimates of these organisms (Kendall Tau = 0.71, 0.58 and0.76 respectively). Conclusion: The new modified dip-slide test kit provides suitable and simple method for screening salivary mutans streptococci, lactobacilli and Candida levels which is useful for early selection of patients for dental examination and would be valuable educational aid for motivation and dietary counseling among children. (Supported by grant from Mahidol University 2001).