GABA-tempeh used in the present study was prepared by aerobic and successive anaerobic fermentation of boiled soybean with Rhizopus microsporus. The contents of free amino acids particularly, g-amino butyric acid (GABA) and oligopeptides in GABA-tempeh were significantly higher than those in conventional tempeh. In this study, the effects of dietary GABA-tempeh on lipid metabolism in rats were compared with casein and soy protein by using high fat diets. It was found that the plasma triacylglycerol levels decreased significantly by consumption of GABA-tempeh compared with soy protein and casein. The higher high density lipoprotein (HDL) and lower low density lipoprotein (LDL) cholesterol levels in the GABA- tempeh group as compared with the other groups favoured the antiatherosclerosis effect of GABA-tempeh. GABA-tempeh is considered to be antihypertensive food since it is particularly rich in GABA. These combined results suggest that intake of GABA-tempeh can prevent lifestyle-related diseases such as hypertension and hyperlipidemia.