This study investigates the impact of waterborne xenobiotics on the rock crab Cancer irroratus. Male rock crabs were caged at two polluted sites for five weeks. One site was highly polluted while the other was slightly polluted mainly by metals. A control group was caged in a raceway tank supplied with clean sea water. The activity of branchial ATPases was increased in crabs exposed to pollution, presumably to compensate for the competition of metals with electrolytes and to facilitate the transport of metals out of the cytoplasm. The rock crab was characterized as having high basal levels of glutathione in the digestive gland (∼ 3500 nmol GSH equivalents/g dry weight). Exposure to waterborne pollutants failed to trigger an increase in glutathione concentration, but over time in crabs caged at the highly polluted site it elicited a 26% increment in the relative mass of the digestive gland which is an important site for glutathione synthesis. Neither cytochrome C oxidase, nor lactate dehydrogenase activity in the merus muscle was affected by pollution. By the end of the experiment, somatic growth rate was highest in the control crabs though the crabs caged at the polluted sites also maintained a positive energy balance. Gonadal growth was delayed at the highly polluted site but the size of the gonads caught up with that of the controls by the termination of the experiment.