Objective To observe the toxicity of raw Chuanwu （Radix Aconiti） combined with raw Banxia （Rhizoma Pinelliae） in different proportions on myocardium. Methods Fifty SD rats were randomized into the normal control group

1∶0 combination group

1∶0.25 combination group

1∶0.5 combination group and 1∶1 combination group

with 10 in each. The combination groups were given 0.4ml/100g of corresponding concentration drugs. The normal control group was given the same volume of normal saline. The intragastric administration lasted for 4 consecutive weeks. The body mass growth rate and heart coefficient were calculated and the cardiac enzymes were detected before administration and after 4-week administration and 2-week withdraw. Results There was no significant difference between groups in the body mass growth rate after 4-week administration and 2-week withdraw （P>0.05）. Comparing with the normal control group

the heart coefficient in the combination groups was significantly increased after 4-week administration （P<0.05 or P<0.01）. Comparing with the normal control group

the heart coefficient in the 1∶0 combination group and 1∶0.5 combination group was significantly increased after 2-week withdraw （P<0.05）. The cardiac enzyme levels in the combination groups were significantly higher than those in the normal control group after 4-week administration and 2-week withdraw （P<0.05 or P<0.01）. Some of the cardiac enzyme levels in the 1∶0.25 combination group

1∶0.5 combination group and 1∶1 combination group were significantly lower than those in the 1∶0 combination group （P<0.05 or P<0.01）. Conclusion Raw Chuanwu is obviously toxic to rat heart. Combined with raw Banxia

the toxicity of raw Chuanwu to heart is greatly reduced. The higher the proportion of raw Banxia in combination

the lower toxicity to the heart.