The objective of this study was to compare ruminal starch disappearance rates of hull-less barley, hulled barley, and corn grains. Five different genotypes were used for each of the 2 barley types. In addition, each of these genotypes was grown in 2 different locations and years, resulting in a total of 10 independent barley samples for each of the 2 barley grain types. Also, 5 different genotypes of corn grain were obtained from a commercial seed company. After grinding to pass through a 4-mm screen of a cutter mill, 3.6 g of grain were placed into porous bags, which were then incubated in the rumen of 2 ruminaly cannulated cows for 0, 4, 8, 12, 24, and 48 h. Corn grains showed greater instant ruminal dry matter (DM) disappearances than barley grains (26.3 and 15.0%, respectively). Instant ruminal DM disappearances did not differ between hulled and hull-less barley grains. Ruminal DM fractional disappearance rate was greatest for hull-less barley grains, medium for hulled barley grains, and lowest for corn grains (10.6, 8.5, and 5.9%/h, respectively). Ruminal DM half-life was shortest for hull-less barley (5.1 h) and longest for hulled barley and corn grains (6.6 h). Ruminal DM half-life did not differ between hulled barley and corn grains. Corn grains showed greater instant ruminal starch disappearances than barley grains (22.5 and 8.3%, respectively). Instant ruminal starch disappearances did not differ between hulled and hull-less barley grains. Ruminal starch fractional disappearance rates were greatest for hulled barley grains, medium for hull-less barley grains, and lowest for corn grains (15.1, 13.7, and 6.9%/h, respectively). Ruminal starch half-life was shortest for hulled and hull-less barley grains (4.4 h) and longest for corn grains (6.6 h). Ruminal starch half-life did not differ between hulled barley and hull-less barley grains. In conclusion, this study showed that starch from hull-less barley grains has a ruminal half-life similar to that of hulled barley grains and shorter to that of corn grains.