Partially hydrolyzed guar gum (PHGG) has a number of properties associated with dietary fiber. PHGG ingestion results in not only an increase in defecting frequency and softer stools in persons with constipation but also significantly improvement of diarrhea in patient with gastrointestinal intolerance. The lowering of fecal pH by intake of PHGG resulted in the growth of Lactobacillus spp. and Bifidobacterium spp., intestinal flora good for human health. Improvement of balance of intestinal microflora resulted in prevention from infection and colonization of Salmonella enteritidis. Further the ingestion of PHGG promoted absorption of mineral and lowered serum cholesterol and triglycerides in the rat and serum cholesterol in human by improving lipid metabolism without reduction of protein utilization. In addition, PHGG significantly reduced the level of plasma glucose, and thereby improved acute post-prandial plasma glucose and insulin response. All these observations suggest that the PHGG is prospective one of dietary fiber with various biological functions.