β, β-dimethylacrylalkannin is a major active chemical component extracted from Lithospermum erythrorhizon, a traditional Chinese medicine that exhibits strong antimicrobial, anti-cancer and anti-inflammatory activities. However, its potential toxicity has not been rigorously studied. To confirm its safety, the oral toxicity of β, β-dimethylacrylalkannin was evaluated in vivo. An acute oral toxicity study in mice demonstrated that β, β-dimethylacrylalkannin was practically nontoxic based on its high median lethal dose (LD₅₀ > 10 g/kg). No deaths or abnormal responses were observed in the acute toxicity test using Wistar rats, suggesting that the maximum tolerated dose of β, β-dimethylacrylalkannin was greater than 10 g/kg. Chronic toxicity studies also revealed an absence of mortality and clinical symptoms, and no treatment-related adverse effects were detected by hematology, blood biochemistry and urinalysis examinations in all rats treated with 10-160 mg/kg/day β, β-dimethylacrylalkannin during a 6-month period. Increases in the relative organ weight of the lungs of females and the liver of males were observed at 160 mg/kg. Histopathological analyses revealed brown pigmentation in renal tubular epithelial cells at the middle and high doses (40-160 mg/kg/day). The no-observed-adverse-effect level (NOAEL) of β, β-dimethylacrylalkannin is 10 mg/kg/day. These results suggest that β, β-dimethylacrylalkannin is potentially safe for further development as a therapeutic agent in humans.