The present study was conducted to investigate the effect of sea tangle and hypoglycemic agent on lipid metabolism in normal and dabetic rats. Male Sprague-Dawely rats were fed AIN-76 based experimental diets containing 5%(w/w) cellulose or 15%(w/w) sea tangle for 3 weeks, after which diabetic groups were made diabetic by intramuscular injection of streptozotocin(STZ, 45mg/kg BW). Metformin(350mg/kg BW) as a hypoglycemic agent was given once a day using a feeding tube for 5 days. Body weight grains were reduced significantly by STZ treatment, but not influenced by metformin feeding. Blood glucosel levels in sea tangle groups were reduced, compared with those in cellulose groups. Metformin feeding showed the lowering effect of blood glucose. Plasma levels of triglyceride were increased significantly in diabetic rats, but decreased in metformin group by sea tangel feeding. Total cholestero contents showed a similar tendency with triglyceride, but were reduced in diabetic groups without metformin by sea tangle feeding. Plasma levels of HDL-cholesterol were reduced in diabetic rats, compared with those in normal rats. There was a significant increase in fecal weights in diabetic rats fed sea tangle. Fecal contents of cholesterol were lower in diabetic rats than in normal rats. In normal rats, it tended to increase by sea tangle feeding, but not significantly. Fecal excretions of coprostanol and coprostanone were reduced significantly in diabetic rats, compared with those of normal rats. It tended to increase in diabetic rats by simultaneous feeding of sea tangle and metformin, but not significantly. Diabetes reduced fecal excretion of bile acid, but it was increased by sea tangle and metformin feeding.