The hypoglycemic effects of red ginsgeng-chungkukjang plus seaweeds, green laver and sea tangle, in streptozotocin (STZ)-induced diabetic rats were investigated. Five groups of male Sprague-Dawley rats weighing $140pm10$ g (10 animals/group) were fed for four weeks with the following: nondiabetic control (NC group); STZ-induced diabetic (D group); diabetic rats fed 3% red ginseng (20%, w/w)-chungkukjang (D-RC group); diabetic rats fed RC containing 10% (w/w) green laver powder (D-RCG group); diabetic rats fed RC containing 10% (w/w) sea tangle powder (D-RCS group). Partially normalized body weight gain, FER, and blood glucose levels were observed in the D-RC, D-RCG and D-RCS groups as compared to the D group. In these three groups, serum levels of triglycerides, total cholesterol, and LDL-cholesterol were found to be lower than in the D group, whereas HDL-cholesterol levels increased. Serum insulin level in D was significantly lower than that of NC, although D-RC, D-RCG, and D-RCS almost recovered to the NC. Serum ALT activity was markedly increased in the D group, while the serum ALT levels in the D-RC, D-RCG, and D-RCS were almost the same as the NC group. Due to diabetes, hepatic xanthine oxidase (XO) activity was significantly increased and administration of red ginseng-chungkukjang or seaweeds resulted in decreased levels of the XO activity. Activity of hepatic antioxidant enzymes (superoxide dismutase and glutathione peroxidase) were significantly decreased in the D group, but the activity in the D-RC, D-RCG, and D-RCS groups were similar to that of the NC group. Results of the present study indicate that supplementation of red ginseng-chungkukjang with seaweed after the onset of diabetes ameliorated hyperglycemia via an increase in serum insulin.