Four rumen-fistulated Merino sheep and four rumen-fistulated Alpine goats received 1.04 kg dry matter of each of the diets over two experimental periods. The daily evolution of ruminal pH was measured. Digestibility was determined by total faecal collection and Cr and Co were used as markers to estimate digesta passage rates. Apparent digestibility of organic matter was higher for the C80 diet, with no differences between sheep and goats. Sheep presented a lower liquid fractional outflow rate from the rumen than goats, as their saliva production is lower. Accordingly, rumen pH tended to be lower in sheep than in goats. In both species the estimated daily saliva production was greater for C20 than for C80 diet. Particulate passage rate from the rumen was also lower in sheep. It is concluded that when sheep and goats were fed high quality diets at low intake levels, significant differences between the two species were observed on the liquid and solid digesta flow kinetics, but not in their digestive capacity.