Five castrated male goats (average BW 21.3 kg) with cannulae in the rumen and proximal duodenum were used to study the influence of intraruminal infusion of the polyether ionophore, hainanmycin (0.05 mg kg^-1 BW day^-1), on rumen characteristics and total tract digestion. Infused hainanmycin did not affect total volatile fatty acid (VFA) concentrations in the rumen, but increased (P<0.05) the molar proportions of propionate from 21.8 to 26.3% and decreased (P<0.05) that of acetate from 72.8 to 68.8%. The ratio of acetate to propionate significantly declined (P<0.01) in the experimental period. Ruminal and duodenal chyme ammonia N (NH₃-N) levels were reduced (P<0.05) 39.5 and 16.0%, respectively, and the chyme urea-N concentration was reduced (P<0.05) 56.8%o compared to the control. Infusion of hainanmycin had no effect (P>0.05) on apparent digestibility of dry matter (DM), organic matter (OM) or acid detergent fibre (ADF) in comparison with the control, but apparent nitrogen (N) digestibility was markedly increased (P<0.05) from 46.1 to 56.4% in the hainanmycin infused period.