Expansion of the biodiesel industry worldwide has increased availability of crude glycerin, a major by-product of biodiesel production from animal and vegetable oils. Our objective was to evaluate DMI and apparent total-tract digestibilities of DM, OM, and NDF in crossbred heifers fed finishing diets in which 15% crude glycerin was used to replace a portion of dry-rolled corn. Twenty-four crossbred heifers (334.4 ± 0.9 kg initial BW) were randomly assigned to 12 pens and allowed ad libitum access to isonitrogenous finishing diets containing 10% corn silage and 90% concentrate composed of dry-rolled corn, soybean hulls, corn gluten feed, soybean meal, mineral premix, and 0 (CON) or 15% crude glycerin (GLY). Glycerin contained 81.5% glycerol, 13.3% water, 6.3% ash, and <0.02% methanol. Animals were fed chromic oxide (0.1% of diet DM), and fecal grab samples were collected 3 times daily (8, 16, and 24 h after feeding) on d 7, 21, and 35; composited by animal; dried; and ground through a 1-mm screen. Chromic oxide contents of feces and diets were determined by atomic absorption and used to calculate apparent total-tract digestibilities of DM, OM, and NDF. Weights of feed DM delivered and refused were recorded daily to calculate DMI. Data were analyzed as a completely randomized design with repeated measures using a mixed model with diet, time, and diet × time as fixed effects, and animal within diet × time as a random effect. There were no interactions between treatment and time of sampling (P > 0.10), suggesting no adaptive response to dietary glycerin. Feed DMI was similar among treatments (10.93 and 10.92 kg/d for CON and GLY, respectively; P > 0.1). Organic matter digestibility of GLY diet was greater than that of the CON diet (P = 0.04), and DM digestibility followed a similar trend (P = 0.06). Digestibility of NDF was unaffected by glycerin addition (P > 0.10). Crude glycerin can effectively replace dry-rolled corn in diets for beef heifers when fed at 15% of diet DM, improving OM digestion without adversely affecting NDF digestibility.