Nine rumen fistulated ewes fed lucerne hay were intra-ruminally dosed for a period of 51 days with 0 (Q₀), 35 (Q₁) and 70 (Q₂) g of quebracho condensed tannin (CT) extract/kg feed daily. Lucerne hay in situ DM, N and NDF 24 h disappearance were significantly lower (P<0.05) in those sheep dosed with the highest level of quebracho extract (Q₂) compared with the other two groups (Q₀ and Q₁). The rumen ammonia-N concentration was also lower in groups treated with quebracho. Neither of the doses affected in vivo DM, NDF or ADF digestibility. However, both reduced apparent CP digestibility (P<0.01). Faecal analyses showed a 30% recovery of the administered CT, regardless of the dose (P>0.10). There were no signs of intoxication by tannins in any of the treatments.