Carassius auratus bred in clean water were selected to conduct active biomonitoring (ABM) exposures in Meiliang and Gong bays in the northern polluted area of Taihu Lake. The biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST), antioxidant enzymes glutathione peroxidase (GP(X)), reduced glutathione (GSH) content and superoxide dismutase (SOD) and lipoperoxidation (as TBARS) in liver were determined as biomarkers during the field exposure period. At the same time, the contents of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and heavy metals in the surface sediments of biomonitoring sites were measured. The total PAH concentrations ranged from 248.8 to 375.9microgkg(-1) dry weight, PCB from 1.26 to 2.41microgkg(-1), OCP from 0.15 to 2.06microgkg(-1), and heavy metal from 126.3 to 210.0mgkg(-1). The results indicate that complex pollution by persistent organic pollutants and heavy metals is present in the northern end of Taihu Lake and the in situ exposed organisms were stressed. Moreover, Meilaing Bay is a more stressful place to fish living there. The integrated biomarker response (IBR) was calculated by combining different biomarkers to single value, which can be used to describe the toxically-induced stress level of populations in different areas. Pollutant concentrations were displayed as star plots and compared to IBR star plots. There was a visual correlation between the PCB gradient and the OCP gradient measured in the sediments and the IBR variation.