Objective: To investigate the relationship between changes of chemical components and diuretic effect before and after salt processing Alisma orientalis from different habitats. Method: Thin-layer chromatographic (TLC) method and high performance liquid chromatographic (HPLC) method were used to detect the changes of chemical components of A. orientalis from difference habitats before and after salt processing. Meanwhile

the diuretic effect of these samples was observed by the metabolic cage collecting method. Result: TLC results showed that there was a great variation in the kind and content of A. orientalis from difference habitats before and after salt processing. But there was no significant difference in HPLC result. A. orientalis from Fujian

whether unprocessed or processed

could markedly decrease the urine volume in normal rats. Unprocessed A. orientalis from Jiangxi had no effect on the urine volume but could be significantly decreased by salt processed A. orientalis. Both before and after salt processing A. orientalis from Guangxi and Sichuan could obviously increase the urine volume in normal rats. Conclusion: The results indicated that the changes of chemical component before and after salt processing A. orientalis from different habitats may be the main factor affecting their diuretic action in the normal rats.