Gastrointestinal effects of feeding 20 g total dietary fiber as wheat bran (WB) and sugarbeet fiber (SBF) were compared in 17 healthy men in a randomized cross-over design. The fibers were milled to similar particle sizes and consumed as supplements to the subjects' self-selected diets (SS). Transit times were similar among the diets. Fecal wet and dry weights were greater on the fiber diets compared to the SS diet (P < 0.05); wet weights were similar with WB and SBF; dry weights were greater with WB than SBF (P < 0.001); and moisture content was lower with WB than SBF (P < 0.01). Fecal pH was lower with WB than SBF (P < 0.025). WB and SBF provided similar fecal bulking effect; however, the contribution of fecal dry matter and fecal water content to increased bulk differed between fibers.