(Principal Investgator), R.M. APRECIO, D. ROBERTS, W. ZHANG, M. LU, M. KIM*, E. HULL*, and E. JOO*, Loma Linda University, Loma Linda, CA •Introduction: Isatis tinctoria, commonly known as Blue Root, is a traditional Chinese herb that has been used to treat various ailments ranging from respiratory infections to gastroenteritis. It has been shown to increase total WBC in addition to increasing the host''s humoral and cellular immune function. The most studied of Isatis tinctoria''s compounds is Tryptanthrin which has been shown to contribute to 5-lipoxygenase inhibition and an inhibitor of COX-2. There have been limited studies involving oral application. •Objective: To determine the antimicrobial effects of Isatis tinctoria on some common oral pathogens. •Material and Methods: Separate experiments were conducted using different extraction methods (Water, methanol, and cottonseed oil) on the Isatis tinctoria. Overnight cultures of bacteria (Streptococcus mutans, Streptococcus oralis, Streptococcus mitis, Enterococcus faecalis, and Staphylococcus aureus.) were plated on agar plates and filter paper discs (1/4 inch diameter) soaked in Isatis tinctoria extract were placed in the agar plates. Chlorhexidine was used as positive control, and phosphate buffered saline was used as negative control. The plates were then incubated overnight at 37°C. Zone of inhibition was measured in millimeters. •Results: Only Chlorhexidine (Positive control) showed zone of inhibition and none of the Isatis tinctoria extracts demonstrated antimicrobial effect to any of the bacterial cultures. •Conclusion: Based on the results of our study, Isatis tinctoria did not show any antimicrobial effects on the tested oral pathogens. Further research should focus on different extraction methods, and the purification of Tryptanthrin compound of Isatis tinctoria.