Nectochaete larvae of the ecologically and economically important ragworm, Nereis virens, were exposed to cadmium, chromium, copper, lead and zinc dissolved in seawater to nominal concentrations ranging from 0 to 5000 µg l !1 . Copper was the most toxic (mean LC 50 of 76.5 µg l !1 ± 95% CI 73.8-79.2 after 96 h exposure) and so was used for subsequent experiments. Exposure of gametes to greater than 500 µg l !1 copper for 2 or 4 h at 10ºC prior to fertilization, or a 10 min exposure during fertilization, significantly reduced embryo developmental success. The effect of copper on larval settlement was also assessed using sediment spiked to a range of concentrations (0, 50, 250, 500, 1000 mg kg !1 dry weight). Significantly fewer larvae were found in sediment of $250 mg kg !1 in comparison to the control or the 50 mg kg !1 treatment. Assessment of living larvae also confirmed a significant reduction in settlement, but in all treatments compared to the control, although the number of dead larvae also increased as the concentrations increased. These effects may have important implications for reproductive success and recruitment of N. virens to polluted sediments.