This experiment was designed to observe some influence on the serum components in rats by feeding basal diet (Protein contents: 20.0%; lipid contents: 3.5%) with soft water (Water, Carbonated cider, Cola and Fanta). Fourty male Albino rats were used as the experimental animals and the subjects were devided into four feeding group and each group was fed on the corresponding diet for six weeks. The contents of protein, lipid and cholesterol were determined in their serum. The obtained results are summarized as follows. 1) The protein contents in the serum was decreased by the feeding of the Carbonated cider, Cola and Fanta compared with Water experimental group. 2) The lipid contents in the serum was similar to each feeding experimental group. 3) The total cholesterol and ester form cholesterol in the serum were decreased by the feeding of the Carbonated cider compared with Water, but were similar to the feeding of the Cola and Fanta.