Ding, S., Oba, M., Swift, M. L., Edney, M., O'Donovan, J. T., McAllister, T. A. and Yang, W. Z. 2015. Short Communication: The effect of seed hardness and malting characteristics on in situ dry matter digestibility of barley grain in beef heifers. Can. J. Anim. Sci. 95: 299-303. An in situ study was conducted to evaluate the relationship between ruminal dry matter digestibility (DMD) and seed hardness or malting characteristics of barley grain. Samples were selected for low and high values of seed hardness index (53 vs. 65; N = 18), beta-glucan content in wort (122 vs. 316 ppm; N = 18), diastatic power (146 vs. 203°L; N = 18), and friability (46 vs. 81%; N = 18) in malt, and incubated in the rumen of three beef heifers for 4, 12 and 48 h. In situ DMD did not vary with beta-glucan concentration or friability. However, barley grain with low seed hardness had lower (P = 0.02) in situ DMD than those with high seed hardness after 4 h of incubation. The barley samples with low diastatic power also had (P = 0.02) higher DMD than with high diastatic power after 4 h, a trend (P = 0.07) that continued after 12 h of incubation. Seed hardness and malting characteristics may have the potential to predict DMD of barley grain in the rumen. However, observed differences in in situ DMD were relatively minor, and we did not detect a relationship between malting characteristics and in situ DMD at longer incubation times. This suggests that the identified grain physical and malt parameters may impact the rate, but not the extent of barley grain digestion in the rumen.