p. 285 - 295 UPTAKE OF 59 Fe, 65 Zn AND 85 Sr BY Mytilus galloprovincialis AND Mya arenaria FROM THE ROMANIAN BLACK SEA SHORE A. S. Bologa Romanian Marine Research Institute Constanta Abstract The concentration factors (CF) of three radionuclides for the marine bivalve molluscs Mytilus galloprovincialis LAM. and Mya arenaria L. have been determined under laboratory conditions. The highest CF for the mussel M. galloprovincialis (adult) are: for 59 Fe=2,245 (shell) and 1,41 (soft parts); for 65 Zn=313 and 2,008, respectively. The highest CF for the soft clam M.arenaria (adult) are: for 59 Fe=303 (shell), 212 (soft parts) and 930 (syphon); for 65 Zn=17,96 and 190, respectively; for 85 Sr=6,6 and 11, respectively. Both species can be considered as possible indicator organisms for radioactive contamination by 59 Fe and 65 Zn in the Black Sea coastal marine environment.