The absorption and translocation of zinc in eelgrass (Zostera marina L.) were examined in a two-compartment system, using 65Zn and autoradiography.The experiments showed that eelgrass absorbed 65Zn and carrier-Zn in the same relative proportions, and that all parts of the plant had the ability to absorb zinc. The concentrations of absorbed zinc in the roots were significantly higher than in the rhizomes. Translocation was extremely low; after 21 days only 0.28 and 0.21% of total absorbed zinc had been translocated to the upper plant parts and root-rhizomes. The translocated zinc was mainly localized in emerging new leaves or in the new roots and younger nodes of the rhizomes. The significance of eelgrass in the cycling of heavy metals in the aquatic environment is discussed, and it is concluded that the translocation of zinc in eelgrass is of minor importance in the exchange of zinc between sediment and water.