Cd and V were analyzed in planktonic species (zooplankton and diatoms), in flocks and in total seston (suspended materials) collected at eleven stations for seven sampling periods in the eastern area of the bay of Seine. Cd concentrations measured in planktonic species of the bay of Seine are identical to those measured in other oceanic areas, but V concentrations are generally higher. In the conditions of sampling, the role of both planktonic species and flocks in the horizontal fluxes of Cd and V in the bay of Seine appears not to be important (Cd) or negligible (V) compared to non-living materials (tripton). Nevertheless, this study should be continued in periods of diatom blooms. Flocks which present high Cd and V concentration probably have an important role in the biogeochemical cycle for both elements in the bay of Seine.