Adult oysters (Crassostrea virginica) were treated for a minimum of 33 weeks with ambient (control), 5, and 15 micrograms Cd/kg seawater at ambient salinity and temperature. After the oysters were induced to spawn, all possible cross-fertilizations between treatments were obtained by mixing the appropriate sperm suspension with the selected egg-seawater treatments. Despite cadmium concentrations as high as 270 micrograms Cd/kg dry weight in the total soft parts, oysters spawned heavily. A minimum of 93% of the embryos resulting from control parents developed into normal larvae when incubated in ambient seawater. As much as 29% of the embryos from control parents failed to develop, or developed into abnormal larvae upon incubation in 15 micrograms Cd/kg seawater. Twenty-four percent of the embryos resulting from the parents treated with seawater containing 15 micrograms Cd/kg developed into abnormal larvae when incubated in seawater containing 15 micrograms Cd/kg. Under the conditions of this study, it appears that seawater containing 15 micrograms/kg of cadmium has a greater impact on embryonic development than on gametogenisis.