We conducted three growth trials to evaluate replacing carbohydrate sources with enzymatically modified potato starches in diets for weanling pigs. In Exp. 1, 180 pigs (initially 5.3 kg and 21+/-2 d of age) were used to compare the effects of corn (36.5%), edible-grade oat flour (36.5%), two enzymatically modified potato starches (12%), and added lactose (12%) on pig performance. Potato Starch 1 had a dextrose equivalent (DE) of 6 and Potato Starch 2 had a DE of 20; both were spray-dried maltodextrans. Pigs that were fed Potato Starch 2 had greater (P<.05) ADG and ADFI than pigs fed diets that contained corn or oat flour from d 0 to 14 after weaning, and pigs fed either Potato Starch 1 or added lactose had intermediate ADG and ADFI. However, for the overall trial (d 0 to 35), no differences (P>.10) in growth performance were observed. In Exp. 2, 198 pigs (initially 4.3 kg and 19+/-2 d of age) were used to determine whether modified Potato Starch 2 could replace a portion of the corn or lactose in the diet. The control diet contained 10% dried whey, and additional treatments were formulated by adding 7 or 14% modified Potato Starch 2 or lactose in place of corn. A positive control diet was formulated containing 29% dried whey. From d 0 to 14 after weaning, increasing dietary lactose improved (linear, P<.04) ADG and ADFI. Increasing the potato starch had no effect on ADG but increased ADFI (linear, P<.02). In Exp. 3, 180 pigs (initially 3.9 kg and 14+/-3 d of age) were used to evaluate Potato Starch 2 or 3 (DE = 30, a spray-dried glucose syrup) as replacements for either corn or lactose in the diet. Pigs were fed a control diet containing 15% dried whey and 12% added lactose. Twelve percent modified Potato Starch 2 or 3 replaced either corn or lactose in the diet on a wt/wt basis. From d 0 to 14 and d 0 to 21, pigs fed either modified potato starch substituted for corn had greater (P<.07) ADG than those fed the control diet. Pigs fed diets with either modified starch substituted for lactose had similar ADG as those fed the control diet. These results suggest that when substituted for corn, Potato Starch 2 can improve growth performance of weanling pigs.