Objectives : The objectives of this study was to obtain acute information (single oral dose toxicity) of Red-Koji (Monascus purpureus 12002) Fermented Scutellariae Radix Aqueous Extracts (fSR), has been traditionally used in Korean medicine for treating various diseases including inflammatory diseases. Methods : In order to observe the 50% lethal dose (LD50), approximate lethal dosage (ALD) and target organs, fSR powders were once orally administered to female and male ICR mice at dose levels of 2,000, 1,000, 500 and 0 (control) mg/kg (body weight.). The mortality and changes on body weight, clinical signs and gross observation were monitored during 14days after single oral treatment of fSR with organ weights and histopathological observations of 12 types of principle organs. Results : After single oral treatment of fSR, we could not find any mortality and toxicological evidences up to 2,000 mg/kg treated group, the limited dosages in rodents, on the body and organ weights, clinical signs, gross and histopathological observations, except for some accidental findings. Conclusions : The results obtained in this study suggest that the LD50 and ALD of fSR in both female and male mice after single oral treatment were considered as over 2,000 mg/kg because no mortalities were detected up to 2,000 mg/kg and can be safety used in clinics.