Rat pups developed chronic protein insufficiency resulting from malnutrition diet in utero while their dams received 40 g protein/kg diet. 2. Before weaning they were found to have decreased salivary amylase (EC 3.2.1.1) and aminopeptidase activities. 3. A complete diet (250 g protein/kg) rapidly restored salivary amylase activity before weight normalization. However, renourished pups (malnourished pups given 250 g protein/kg for 14 d) still had increased numbers of Streptococcus multans in their plaque.