AIM: To evaluate the pharmaceutical safety of a Chinese herbal formula, Chunggan extract (CGX), traditionally prescribed as a hepatotherapeutic drug via systemic acute and subacute toxicological study.METHODS: Twenty male dogs and 20 female dogs were fed doses 50 times and 4 times greater than the clinically-recommended drug dosages in an acute and a subacute toxicological study, respectively. Adverse effects were examined by comparing the differences between normal and drug-administered groups using clinical signs, necropsies, histopathologic findings, haematology,urinalysis, and biochemical analysis.RESULTS: In the acute study no change in the body weight, diarrhoea, apetite, mortality rate and histopathology of major organs was observed in male or female dogs with a single administration of CGX at 5 g/kg. No drug-induced abnormalities at analysis of histopathology,haematology, urinalysis, and biochemistry were found with any dose of this drug.CONCLUSION: CGX is supposed to be very safe when used in a clinical application with a wide therapeutic index.