Mature ICR mice were randomly divided into groups and treated with various doses (1 mg, 5 mg or 10 mg herb/25 g body weight) of a decoction of one of three following Chinese medicinal herbs: Aconitum carmichaeli,
Aconitum kusnezoffi and Tripterygium wilfordii, once daily for 4 days. Twenty four hours after the last injection the animals were bled and the blood samples were stored at -20°C until assay for liver lactate dehydrogenase (LDH) isozyme activity. The livers, kidneys, hearts and gonads were dissected out, immediately fixed in Bouin's fluid, and subsequently processed for histological examination. It was found that the gonads and hearts of the drug-treated mice were histologically similar to those of control ani mals. After treatment with the lowest dose of the herbs i.e. 1 mg/25 body weight, the liver and kidney did not undergo observable changes. However, the herbs at the doses of 5 mg and 10 mg/25 g body weight produced damaging effects on the liver and kidney, the effects produced by the higher dose being more dramatic. The tissue damage was accom panied by elevations of liver LDH isozyme activity in the serum.