Da Cheng Qi Tang (DCQT) is a classical prescription of Chinese medicine for treatment of acute intestinal obstruction. In this paper, the isolated colon smooth muscle from normal and experimental colon obstruction (CO) rats were used to study the effect of DCQT on 45Ca content. The results showed that the 45Ca content on isolated colon smooth muscle (microns/g wet tissue, mean +/- S) was 0.043 +/- 0.009 in the normal and 0.057 +/- 0.012 in those treated by DCQT respectively. The content of 45Ca in CO was higher than the normal, DCQT can reduce the content of 45Ca in CO. It is known that the higher level of intracellular CA++ is related to the formation and the development of acute intestinal obstruction. The inhibitory effect of DCQT on 45Ca content may play an important role in the treatment of acute colon obstruction.