Proline-rich proteins (PRPs) are major components of human saliva. In order to know the biological roles of PRPs, we explored the expression pattern and functional protein structures of PRPs by the immunohistochemical and various molecular biological methods. Polyclonal antibody against human gPRP was generated from rabbit by the injection of oral exfoliated cells specially treated by urea and SDS buffer. The PRPs began to be expressed both in the acinar cells and ductal cells from the EIDS (Early Intermediate Developmental Stage) of fetal salivary glands and became intense in the salivary epithelium in the LDS (Late Developmental Stage) and adult salivary glands. The polyclonal antibody against the gPRP showed the cross-reactivity with aPRP and bPRP, these results were relevant to the high homology among subtypes of PRP. However, the simulated protein structures of PRPs showed the characteristic repetitive whorling domains except the N-terminal signal peptide. The whorling domains were also contained the multiple amino acids of glutamine and glycine, which may provide the receptor binding or cross-linking sites of PRPs.