The objective was to evaluate the effects of exogenous amylases and proteases on ruminal in vitro dry matter (IVDMD) and starch (IVSD) digestibility of dent corn grain. Two separate experiments were performed to evaluate 10 exogenous amylases (Experiment 1), and 3 exogenous proteases (Experiment 2) using an in vitro batch culture of buffered-rumen fluid. Dried ground (4-mm) dent corn was used as substrate (0.50 g per F57 bag). For Experiment 1, treatments were Control (no enzyme) and 10 different amylases (1LAT, 2AK, 3AC, 4Cs4, 5Trga, 6Afuga, 7Fvga, 8Star, 9Syn, and 10Tg). For Experiment 2, treatments were Control (no enzyme) and 3 different proteases (11P14L, 12P7L, and 13P30L). In each experiment, each enzyme was applied at 0.25, 0.50, 0.75, and 1.0 mg of enzyme/g of substrate DM. Samples were incubated for 7 h in quadruplicate per run in 3 independent runs. Data were analyzed for both experiments using the GLIMMIX procedure of SAS. Dose was used as fixed effect in the model while run was considered a random factor. In Experiment 1, enzymes 2AK, 3AC and 10Tg did not increase (P > 0.10) IVDMD and IVSD, whereas the lowest dose of enzymes 1LAT, 5Trga and 8Star increased (P < 0.01) IVDMD by 23, 47 and 62% and IVSD by 35, 41 and 58%, respectively, compared with the control. Enzymes 4CsC, 6Afuga, 7Fvga and 9Syn increased IVDMD and IVSD in a dose-dependent manner (P < 0.01) and some of the greatest increases in IVDMD (82.9%) and IVSD (85.9%) resulted from applying the highest dose of enzyme 6Afuga instead of the Control. In Experiment 2, the lowest dose of exogenous proteases, 11P14L and 12P7L increased (P < 0.01) IVDMD by 98 and 87% and IVSD by 57 and 64%, respectively, whereas the highest dose of 13P30L increased (P = 0.02) IVDMD by 44.8% and IVSD by 30%, relative to the control. Starch and DM disappearance were increased by exogenous amylase and protease addition. Future in vivo studies are required to validate these findings before these enzyme additives can be recommended for improving the digestibility of ruminant feeds.