Concentrations of immunoglobulins and other plasma proteins were determined by radial immunodiffusion in the blood sera and saliva of 16 dysmature (small-for-dates) and of 16 eutrophic healthy infants with an average age of 4.8 and 4.7 months, respectively. The local synthesis of salivary proteins was calculated with a formula used by Deuschl and Johansson for the estimation of local synthesis of bronchial immunoglobulins. The formula was completed by a correction factor established by the authors, based on their previous investigations. Dysmature children had a significantly lower serum IgG, IgA, albumin, transferrin, coeruloplasmin and beta-lipoprotein level. In the dysmature infants the salivary albumin and alpha 1-acid glycoprotein concentration was higher than in the normal controls. A local synthesis of IgA, IgG, transferrin, alpha 1-acid glycoprotein, alpha 1-antitrypsin and haptoglobin was observed in both groups, but the production of these proteins was slightly diminished, while their transudation was more important in the dysmature subjects. The lower level of serum proteins, as well as the lower local synthesis in the salivary glands may be due to the immaturity of the tissues that produce these proteins. The increase of the protein transudation is attributed to a rise of the tissue permeability in the dysmature children which is a late consequence of intrauterine malnutrition.