This study was conducted to determine the effects of different levels of dietary tannin on gastrointestinal tract (GIT) histology and on liver and kidney masses. Five groups of Boer goats were given diets containing 0, 50, 100, 150 and 200 g/kg of tannin for 6 weeks before data collection. Differences in the histopathology of the oesophagus, reticulum, rumen, omasum, abomasum and duodenum were evaluated. Increased dietary tannin levels induced thickening and/or keratinization of epithelial tissue in the reticulum, rumen, omasum and abomasum. Increased tannin levels also resulted in a loss of epithelial cells, erosion of microvilli and shortened villi height in the duodenum, which could impair the absorption of nutrients. Consequently, condensed tannins had a negative effect on the histopathology of the Boer goats.