Second-parity swine were assigned at breeding and continued through two reproduction-lactation cycles (second and third parities, phases one and two) on four dietary treatments as follows: Control (C), 1.8 kg of a standard gestation diet daily (6000 kcal DE daily) to parturition; "Protein-free" (PF), 1.8 kg of a semipurified diet containing less than .5% protein (6000 kcal DE daily) to parturition; Restricted control (R), 0.6 kg of a maize-soybean meal-based gestation diet (C) daily (2000 kcal DE daily) to d 70 of gestation and 1.8 kg daily (6000 kcal DE daily), from d 71 to parturition; Restricted nonprotein calories (RCal), 0.6 kg daily (2000 kcal DE daily) of a diet containing three times the concentrations of protein, vitamins and minerals present in the C diet to d 70 of gestation and 1.8 kg daily (6000 kcal DE daily) of the C diet to parturition. All sows were fed a 16% protein diet ad libitum from parturition to d 28 postpartum. Number of piglets born/litter was unaffected by gestation diet, but individual birth weight was less (P less than .01) in PF than in other progeny in both parities. Postweaning daily weight gain was less (P less than .01) in PF progeny than in other progeny and daily feed intake was less in PF than in C progeny (P less than .05) but intake of PF, R and RCal progeny did not differ. Body weight, chilled carcass weight, carcass length, and weights of trimmed wholesale cuts were less in PF than in other progeny at slaughter. It is concluded that severe protein restriction throughout pregnancy reduces postweaning weight gain of progeny, and that restricting nutrients other than protein and nonprotein calories to one-third of intake recommended by the National Research Council during the first two-thirds of pregnancy does not affect postweaning body weight gain of progeny of swine whose response to the nutritional insult does not result in reduced piglet birth weight.