We examined the effects of tannins on food digestion in the plateau zokor (Eospalax baileyi), a rodent that lives primarily underground. Our results indicate that (1) all experimental groups maintained their body weight; (2) food intake and food assimilation increased, while food digestibility decreased with an increasing tannin concentration in the diet; (3) protein digestibility, but not protein assimilation, decreased significantly with an increasing tannin concentration in the diet; (4) mean dry weights of the small intestine of the zokors fed with feed containing 3% and 6% tannic acid were 67% and 87%, respectively, greater than that of the control. Therefore, tannins in the diet affected negatively food and protein digestibility in zokors. The animals counteracted these effects and maintained their body weight and nutrient assimilation by increasing food intake as well as widening the lumen of their small intestine.