Our aim was to evaluate the effects of exogenous amylase on the in vitro (bath culture, 96 h of incubation period) ruminal digestion kinetics of whole-crop corn silage harvested at late maturity stage. Two corn hybrids were evaluated: RB9004 – dent type harvested at 110 (375 of DM; 65.2 of CP; 475 of NDF; 383 of NFC g/kg in DM basis) and RB9308 – flint type harvested at 105 d after sowing (348 of DM; 72.6 of CP; 503 of NDF; 337 of NFC g/kg in DM basis). The in vitro tests were performed using rumen fluid from 2 nonlactating rumen fistulated cows fed diets composed of 53:47 forage:concentrate ratio (180 g/kg CP and 300 g/kg NDF), and mineral premix containing the treatments: control (without amylase) or amylase (0.7 g/kg DM of Ronozyme Rumistar; DSM Nutritional Products Brazil). The 2 cows were changed over between the 2 treatments and the rumen fluid were collected after 14 d of adaptation. The experimental design was split plot on random complete blocks, where the blocks were the rounds (2), addition or not of amylase were the plots and the hybrids (2) were the subplots. Digestion parameters were obtained by bicompartimental logistic model describing the digestion kinetics of NFC and fibrous carbohydrate (FC) fractions. Amylase increases (10%) gas production of NFC fraction in both hybrids (160.5 vs. 145.5 mL, P = 0.002). The gas production of FC fraction increased in dent hybrid (P = 0.016) with no difference in flint hybrid. In both hybrids, amylase increased in 12.5% gas production rate of NFC fraction (2.43 vs. 2.16%/h, P < 0.001) and in 16% the gas production rate of FC fraction (10.3 vs. 8.9%/h, P < 0.001). Amylase decreased the total gas production in dent hybrid (252 vs. 275 mL), and increased in flint hybrid (265 vs. 236 mL). The in vitro dry matter digestibility (IVDMD) increased 6% in amylase treatment in both hybrids (616 vs. 582 g/kg of DM; P = 0.002). Exogenous amylase improves ruminal digestion kinetics and increase IVDMD of whole-crop corn silages harvested at late maturity stage.