The effects of ingestion of young barley insoluble dietary fiber concentrate (BDFC) on cecal production of short-chain fatty acids (SCFA), fecal output and organ weight were examined in rats. The rats were fed either a control diet containing 5% cellulose powder or experimental diets containing 4.7, 7.8 or 15.7% BDFC (dietary fiber in BDFC accounting for 3, 5, or 10% of the diet, respectively) for 4 weeks. Although there was a significant difference in cecal n-butyrate concentration between the control and 4.7% BDFC groups, the fecal concentration of each and total SCFA, and the weight and pH of the cecal contents did not vary significantly among the 4 groups. There was a significant negative correlation (r=-0.518, p=0.002) between colo-rectal transit time and fecal dry weight in rats fed the experimental diets containing different levels of BDFC. Fecal wet weight and fecal dry weight of rats in the 7.8 and 15.7% BDFC groups were significantly higher than those of control rats. BDFC had a dose-dependent effect in increasing fecal weight (r=0.885, p<0.001) and fecal dry weight (r=0.973, p<0.001). These increases of fecal weight and improvements of bowel movement were probably attributable to the insoluble dietary fiber in BDFC.