Chestnut tannins are rich in hydrolysable polyphenols. In piglets, the use of phenolic compounds is known to reduce weaning stress. Their antioxidant, anti-inflammatory and antimicrobial properties are known to improve piglet intestinal health, but these results seem to depend on the quality of the tannins used. In this study, we thus compared three chestnut tannins (A, B and C) of different geographical origins for several criteria: content of three major hydrolysable polyphenols (gallic acid, ellagic acid, and vescalagin), antioxidant capacity, content of total reduced sugars and of monosaccharides. Tannin B was significantly (P < 0.05) richer in ellagic acid (9.9 mg/g) and gallic acid (36.2 mg/g) than Tannin A. Tannin C had less gallic acid (28.9 mg/g) but significantly (P < 0.05) more vescalagin (61.9 mg/g) than Tannin B. The antioxidant capacity of Tannin B was significantly (P < 0.01) higher than that of Tannin A. Tannin B had a higher content of reducing sugars in glucose equivalents (215.7 mg/g) than Tannin A (151.6 mg/g) and Tannin C (159.3 mg/g). These tannins were composed mainly of xylose and glucose, and their content was higher than that of Tannin A. The contents of hydrolysable polyphenols and sugars depended greatly on the origin (e.g., geographical area, climate) and process used to extract tannins (e.g. temperature). Due to such differences, this point could influence the effectiveness of these natural extracts when added to pig feed and could explain the variability in effectiveness of tannins on the digestive health of weaning piglets described in the literature.