Abstract: Objective To compare clinical parameter differences in heart and kidney between rats drinking purified water and boiled tap water.Methods Wistar rats before their born were supplied with purified water and boiled tap water respectively for 20 weeks.Rats were sacrificed at the end of the experiment.Body weight,organ weight of heart and kidney,hematological parameters,related clinical biochemistry parameters,and histopathological changes of heart and kidney organs were observed.Results Compared with the same sex rats that dank boiled tap water,the males mean body weight significantly increased(P<0.05),and the females blood triacylglycerol and cho lesterol significantly increased(both P<0.05).Concomitantly,blood plasma creatinine and urea nitrogen decreased very significantly(P<0.01),and urea acid and phosphers decreased significantly(P<0.05)for males,but only urea acid decreased significantly(P<0.05)for females.In additional,slightly pathological changes in myocardial cell and typical hyaline cast in kidney tubules were obser ved in the rats that drank bottled purified water.In contrast,the rats given boiled tap water showed no such variation.Conclusion Long-term intake of pur ified water can cause biological effects on heart and kidney.