The present study aimed to evaluate the effect of replacing corn with high-tannin sorghum grain in the diet of steers on ruminal degradation of dry matter and fibrous fraction. Four rumen-fistulated cattle with a mean body weight of 519 ± 31 kg were used in this study. These animals were divided into groups using a 4 ´ 4 Latin square experimental design. Animals received four different diets in which increasing levels of ground corn were replaced with high-tannin sorghum grain in the proportions of 0%, 33%, 67% and 100% in the concentrate. Dry matter (DM) and neutral detergent fiber (NDF) were measured by in situ incubation of sorghum grain samples. Rumen residue was analysed for DM and NDF disappearance at incubation times of 0, 6, 12, 24, 48, 72, 96, 120 and 144 h. A quadratic behavior was observed in the fraction “c” of the DM and soluble fraction "a" of the NDF of the sorghum grain in function of the replacement levels of corn for high-grain tannin sorghum. Rumen DM and NDF degradability of sorghum grains with high tannin content up to 144 h showed an increasing behavior for all levels of inclusion of sorghum in the diet. The replacement level 67 showed the maximum DM and fibrous fraction disappearance of sorghum grain up to 144 h of incubation. Sorghum grain achieved maximum ruminal dry matter degradation and the fibrous fraction at the 67% replacement level of ground corn by high-tannin sorghum grain in the diet of steers.