The purpose of this study was to investigate the effect of dietary sea-tangle extracts on blood glucose levels, serum lipid levels, thiobarbituric acid reactive substance (TBARS) and glutathione enzymes in diabetic rats treated with streptozotocin (STZ) Four groups of rats (Sprague-Dawley male rats, 180 - 200g) were consisted of normal rats fed control diet (C), diabetic rats fed control diet (CD), normal rats fed sea-tangl extracts diet (E), and diabetic rats fed sea-tangle extracts diet (ED). Diabetes was induced by single injection of streptozotocin (60 mg/kg B.W.). After 7 weeks, rats were sacrificed, serum glucose, serum total cholesterol, triglyceride levels and glutathione enzymes were measured. Urine was significantly higher in CD and ED groups than those of others (p < 0.05). Levels of amylase, calcium, uric acid, hemoglobin, cholesterol and low density lipoprotein (LDL)-cholesterol were different among four groups. But high density cholesterol (HDL)-cholesterol of ED group was significantly higher (p < 0.05) than other groups (C and E group) And the weekly change of serum glucose was decreased in the 3th,4th and 5th weeks. But serum triglyceride (TG) of diabetic rats fed sea-tangle extracts diet (ED) was lower than diabetic rats fed control diet (CD). Activity of hepatic microsomal G6Pase was significantly increased CD and ED groups higher than C and E group, but kidney was decreased ED group. Hepateic glutathione S-transferase (GST) of CD and ED group were significantly lower than C and E group (p<0.05), glutathione peroxidase (GPX) of E and ED group were significantly higher than C and CD group (p<0.05), glutathione reductase (GR) activities of ED group was significantly lower than other groups, malondialdehyde (MDA) of ED was lower than E and CD group, but kidney was increased significant in ED group compared to liver. These results suggested that dietary sea-tangle extracts reduce .hepatic disorders such as oxidant than kidney. In conclusion, dietary sea-tangle extracts groups reduced blood TG and hepatic MDA levels in STZ-induced diabetic rats.