The ultimate aim of this study is to find high-fiber sources among Korean common foods and to develop a high-fiber supplement which can be useful in the therapeutic diet for the diabetic patients. For this purpose the effect of four kinds of seaweeds(mixture of purple laver & sea lettuce : MPS, sea tanle : ST, sea mustard : SM, agar agar : AA) on the glucose and lipid mtabolism were examined. Seven groups of normal and streptozotocin-induced diabetic rats were fed dietary fiber-free control diet or one of experimental diets containing 7% of one of four seaweeds for six weeks. The effects of seaweeds were campared with the effects of fiber-free diet or pectin diet. ST, SM, and AA showed a tendency of improving glucose tolerance improvement by those seaweeds, however, was less than that by pectin. MPS was found to possess a serum cholesterol-lowering effect which is comparable to that of pectin. All the supplementations of seaweeds induced significant increase in fecal steroids excretion. The amounts of fecal cholesterol excretion follwing in feeding of MPS and SM were as high as the level cause by pectin. The excretion of bile acids in the MPS group was much higher than that in the pectin group. Based on its effects of alleviating the diabetic symptoms in the previous study and of improving the glucose tolerance, sea mustard seems to have a benefical effect on glucose metabolism. The serum cholesterol-lowering effect of MPS possibly due to the significant increase in fecal steroids excretion suggests that MPS may be effective in improving abnormalities of lipid metabolism. Therefore, sea tangle and mixture of purple laver & sea lettuce seem to be promising as an effective source of high-fiber supplement for the diabetic patients.