The distribution of carbohydrates on the surface of freshwater and marine bivalve gametes was examined based on labeling by 5 lectins. The 3 species of interest were Dreissena bugensis, Mytilus galloprovincialis, and Crassostrea virginica. The lectins used to identify the surface carbohydrates are Arachis hypogaea (PNA), concanavalin A, Griffonia simplicifolia, Lens culinaris (LcH), and wheat germ agglutinin. Live eggs and sperm from each species were examined for lectin affinity. Lectin labeling differed greatly between the 3 species, with very few, if any, conserved trends. Furthermore, there was no obvious difference in labeling between marine and dreissenid species. Of particular interest were LcH labeling of M. galloprovincialis sperm that labeled the tip of the outer sperm acrosome and PNA labeling of C. virginica gametes that was specific only to the sperm inner acrosomal membrane. Fertilization series looking at the distribution of PNA labeling of the sperm acrosome showed localization to the basal ring associated with sperm-egg binding.