Brewer's yeast cell wall (BYC) is a valuable foodstuff that prevents constipation in rats. In this study, the effects of yogurt supplemented with brewer's yeast cell wall (BYC-Y) on constipated male Sprague-Dawley rats induced by loperamide (2 mg/kg body weight) were investigated. The preventive effect of BYC-Y on experimentally constipated rats was examined and compared with that of nonfiber diet (Control) and standard yogurt (Yogurt) as the control diets. The number of feces and fecal dry weight were greater in rats fed with BYC-Y than in those fed with Control or Yogurt. Moreover, the effect of BYC on the improvement of cecal microflora in constipated experimental model rats was evaluated. The number of Lactobacillus, Eubacterium, and total anaerobes per unit cecal contents increased (p<0.03) as a result of BYC ingestion. These findings indicate that BYC-Y or BYC is effective for the alleviation of constipation and bowel environment.