Digestibility trials were undertaken with pigs weighing 45 kg to compare the nutritive value of dried cooked potato with raw ware potato, potato of high and medium glycoalkaloid content, sprouted and greened potato, and macerated potato centrifuged (dewatered) to remove 84% of the water. There was no effect attributable specifically to either glycoalkaloid, sprouting or greening. In relation to values obtained for cooked potato, raw potato treatments had lower apparent digestibility coefficients for nitrogen and a lower efficiency for nitrogen retention. When potato was dewatered, 84% of the nitrogen, but none of the starch, was lost in the effluent. Chymotrypsin inhibitor activity was high in all the raw potato stocks, but absent in cooked potato. It is suggested that the presence of a chymotrypsin inhibitor contributed to the deleterious effects on nitrogen utilisation which resulted from the inclusion of raw potato into diets.