The present studies were undertaken to investigate the sexual dimorphism of porcine amelogenins and to gain information as to whether excesses of male amelogenins, if any, possess functional significance in protein-crystal interactions. Enamel proteins, including the intact full-length amelogenins and their degraded polypeptides, were isolated from the secretory enamel of male and female pigs. To identify the amelogenins among the separated pools of male- and female-matrix proteins, rabbit anti-C13 and C25 peptide sera were used, which reacted specifically with the conserved C-terminal domain. Immunoblotting showed that a few extra members of the amelogenins, sharing common epitopes at the C-terminus, were recognized in male products. The apparent yield of the male amelogenins was only marginal, on the basis of their stained intensities on the gel, but the secreted male amelogenins demonstrated selective (probably the strongest among the amelogenins) adsorption properties onto apatite crystals. Reflecting the general symmetric electrophoretic profiles of the male- and female-enamel proteins in toto, there were no sex-linked differences in the protein-crystal interaction and the resulting regulatory function of crystal precipitation.