['The effect of grape seed indigestible fraction (GSIF) on cecal enzyme activity was studied.', 'Beta-glucuronidase, beta-glucosidase, azoreductase, nitroreductase and nitrate reductase were measured in the cecal content of adult Wistar rats fed with a fiber-free diet supplemented with 5% cellulose or 5% GSIF as the source of dietary fiber for 4 weeks.', 'The intake of GSIF did not affect body weight gain nor food intake. However, GSIF caused a significant increase in cecal content, cecal wall and fresh and dry stool weight. Bacterial enzyme activities were lower in the GSIF-fed group than in the cellulose-fed group, although the difference was also significant for nitroreductase and beta-glucuronidase.'] Do indigestible components of grape seeds modify cecal enzyme activity in rats?