Research in this field is concerned mostly with the uptake and loss of radionuclides by molluscs. There is a great deal of information on the concentration and concentration factors for the most dangerous radionuclides. But it is very difficult to draw useful conclusions from these data for reasons discussed in the paper. More information is needed on: 1. the evaluation of the total amount of radionuclides present in molluscan populations; 2. the transfer of radionuclides from the environment to molluscs and "vice versa" and 3. the metabolism of the radionuclides. Only studies of this type will make it possible to evaluate the role played by molluscs in the transfer of radionuclides in an ecosysten. Relevant methods are discussed in the paper.