During the first year of an infant's life, the oral environment is subject to drastic changes that coincide with the eruption of teeth. Proteins in saliva are important for protecting oral surfaces and provide receptors for bacterial adhesins. The objective of this longitudinal study was to monitor the general composition and expression of proteins in whole saliva of infants, to prove the hypothesis that expression of certain proteins changes during infant development, and might be associated with tooth eruption. The results showed a remarkable constancy in the overall pattern of salivary proteins and glycoproteins during infancy. Exceptions were the mucins and albumin. The mucins are expressed differentially, with first MUC7 and later MUC5B being predominant. Albumin, a marker of serum leakage, started to rise in whole saliva preceding tooth eruption. Thus, the expression of only few proteins appears to be changed during infant development.