We measured the concentrations of the trace elements B, Mn, V, Co, Cr, Ni, Cu, Zn, As, Se, Mo, Pb and Cd in whiting Merlangius merlangus infested or non-infested with the intestinal helminth Hysterothylacium aduncum, as well as the concentrations in H. aduncum itself using inductively coupled plasma mass spectrometry (ICP-MS). The levels of most trace elements did not differ between the tissues of infested and non-infested fish. The tissues and parasites of younger fish (<2.1 year old), however, carried higher amounts of trace elements than those of older individuals. H. aduncum accumulated all trace elements in greater amounts, up 255 folds, than any fish tissues tested. These results support the idea that the higher metabolic activity of younger fish may lead to higher amounts of trace element accumulation in their tissues. Moreover, trace element accumulation is not cumulative as fish grow, and fluctuates during various life cycle of fish.