Two 15-day old preruminant calves, fitted with reentrant ileocaecal and single colon cannulae, were fed a milk substitute containing 47 p. 100 of toasted soya oil meal, 17 p. 100 of crystallized tallow, 28.5 p. 100 of lactose, 7.0 p. 100 of minerals plus vitamins and 0.5 p. 100 of DL-methionine all on a dry basis. Samples from the ileum, colon and faeces were collected every 2 hrs for 8 hrs after feeding, when the calves 1 and 2 were 4 and 9 week-old, respectively. Total water-soluble carbohydrates were determined, then identified by ion-exchange chromatography. In this preliminary work, we only present results on the healthiest calf. At the end of the small intestine, sucrose and alpha-galactosides were probably poorly digested. Their concentration (as a percentage of total water-soluble carbohydrates) was the same as in the soya bean. In the large intestine, these carbohydrates were completely utilized and the sucrose was break down faster than the alpha-galactosides. The end product of fermentation was mainly lactic acid (4-8 g/l of intestinal contents), and the pH values of the large intestine contents were low (4.0-4.9), but these fermentations did not cause digestive problems, such as diarrhea, probably because the amount of soya carbohydrates in the food was low, and the digestive processes along the digestive tract were very regular.