The presence of condensed tannins (CT) in sorghum grain can limit its use as animal feed. High proportions of tannin-rich sorghum grains in diets may affect intake and digestibility, resulting in low animal performance. Microbial fermentation is able to neutralise these effects and some tannins molecules are degradable in the rumen (Selinger et al., 1996). Other studies indicated positive effects on nutrient absorption and disease control when sheep are fed diets with low concentrations of CT (Aerts et al., 1999). High concentrate diets are commonly used for finishing lambs and sorghum grain is an important source, thus the observation on tannins effect in these diets are important to evaluate possible advantages or negatives effects on the use of tannin-rich sorghum hybrids. The aim of this work was to study the effects of tannin-rich sorghum grain in high concentrated diets for finishing lambs.