Male and female rats born of protein malnourished mothers were fed a low-protein diet (8% casein) for 150 days after weaning and daily food and water intakes and body weights were monitored. Although daily intakes of diet throughout the study were significantly lower than those of rats maintained on a normal protein diet (25% casein) or stock diet, intakes/100 g body weight were significantly greater. Daily increments in body weight, as percent of previous day's weight, were consistently higher in rats fed the low-protein diet in comparison to rats fed the normal protein diet. Marked retardation of body growth was evident throughout the study although feeding efficiency ratios (daily body wt. increment per g daily food intake) were comparable among the various dietary groups. Compensation for reduction of the protein component of the diet by increased daily food intake/100 g body weight did not alleviate growth retardation.