Abstract: The hypothesis tested was that supplementation of the ration with yeast would negate the inhibitory effect of high-fat intake on rumen fermentation in goats. In a 3x3 Latin square-design, three rumen-fistulated goats were given free access to grass silage and either a low-tallow concentrate or a high-tallow concentrate without or with added yeast. Feed intake, apparent fiber digestibility, rumen pH and volatile fatty acids were measured. When the goats were fed the high-fat diet without yeast, dry matter intake with silage was significantly higher than when either the low-fat diet or the high-fat diet with yeast was supplied. The apparent digestibilities of macronutrients were not significantly affected by the dietary treatments. Group-mean digestibility of neutral detergent fiber was lowered by 0.4% units after feeding the high-fat diet without yeast and by 1.3% units when the high-fat diet with yeast was supplied. The ruminal pH and concentrations of volatile fatty acids were not influenced by dietary treatment. It is concluded that the addition of yeast to a high-tallow ration did not improve feed intake and rumen function in goats.