The purpose of this study was to investigate the effect of pretreatment with Saegchinyanghyoltang(SYT) on the serum lipid composition and atherosclerotic index in streptozotocin(STZ)-induced diabetic rats. SYT pretreatment in STZ-induced diabetic rats inhibited the rise of serum glucose concentration. Serum total lipids and triglyceride levels in the STZ -induced diabetic rats were significantly higher than those in the control group. But in the group pretreated with SYT, triglyceride and lipid levels were significantly lower compared with those of STZ -induced diabetic rat group without STZ. However, the serum phospholipid levels were not statistically different among treatment groups. In the STZ-induced diabetic group, the serum total cholesterol, VLDL-, LDL-cholesterol levels and atherosclerotic index Were higher and HDL-cholesterol level was lower compared to the control group. However, these changes were prevented by SYT pretreatment Pretreatment with SYT significantly increased the activities of serum lipase compared to the STZ-treated group.