This paper is a synthesis of our current investigations to evaluate bioaccumulatory characteristics of chondrichthyans. The bioaccumulation of seven heavy metals and radionuclides (241Am, 109Cd, 57Co, 51Cr, 134Cs, 54Mn and 65Zn) from seawater were experimentally compared in the chondrichthyan Scyliorhinus canicula (spotted dogfish) and the actinopterygian teleost Psetta maxima (turbot). Uptake rates varied greatly among isotopes and between species. With the exception of 134Cs, all radiotracers were accumulated at a faster rate in S. canicula than in P. maxima, and were predominantly associated with the dogfish skin. Encased embryos of S. canicula also absorbed these radioisotopes directly from seawater during experimental exposure, demonstrating the permeability of the egg-case to these contaminants. The collagenous egg case was the major repository (69-99%) of all six radioisotopes (not including 51Cr) that were distributed throughout its wall. The case is the major source of gamma radiation exposure to the embryo and potentially of radioisotopes for continued absorption by the embryo. The enhanced capacity for bioaccumulation in the juvenile S. canicula a n d the bioaccumulatory role of its egg case both suggest an enhanced susceptibility for contaminant exposure that is taxonomically based, warranting further bioaccumulation studies on chondrichthyans.