Changes in albumin and antioxidant enzyme mRNA expression in infant rat liver following administration of total parenteral nutrition (TPN) with/without soybean oil emulsion were studied. Infant rats were divided into three groups: group 1=oral diet, group 2=TPN without fat, and group 3=TPN with 20% of calories from soybean oil emulsion. The period of TPN administration was 4 d. Serum aspartate aminotransferase and alanine aminotransferase levels were higher in group 2 than in the other groups, with similar levels seen in the other groups. Albumin, Cu, Zn-superoxide dismutase, and glutaredoxin 1 mRNA expression levels were lower in group 2 than in the other groups, with similar levels seen in the other groups. Catalase mRNA expression was higher in group 1 than in the other groups, with the lowest level seen in group 2. Soybean oil emulsion should be included in TPN regimens to prevent down-regulation of albumin and antioxidant enzyme mRNA expression.