The aim of the study was to assess polycyclic aromatic hydrocarbon (PAH) contamination on the Bílina River (the Czech Republic) by measurement of three PAH biliary metabolites in fish and 16 PAHs in passive samplers. A total of sixty-one fish were collected; the indicator species were chub (Leuciscus cephalus L.; n = 25), roach (Rutilus rutilus L.; n = 17) and brown trout (Salmo trutta m. fario L.; n = 19). Three biliary PAH metabolites were measured: 1-hydroxypyrene (1-OHP), 2-naphtol, and 1-hydroxyphenanthrene, but only 1-OHP was detected in all fish. The highest median value of 32.3 ng·mg -1 of 1-OHP was found at Ústí nad Labem, while the lowest median value of 27.6 ng·mg -1 was found in the control site, Březenec. No significant differences (P < 0.05) among the sites were found. The highest concentration of PAH was detected in Litvínov-Záluží (172.0 ng·l -1 ) and the lowest concentration (7.9 ng·l -1 ) was detected in Březenec. A positive, but non-significant correlation (r s = 0.8) was confirmed between biliary 1-OHP and total PAH in passive samplers. These results indicate the highest pollution in the middle stretches of the Bílina River, especially at Litvínov-Záluží. We confirmed 1-OHP as the most prevalent PAH biliary metabolite in fish that could be used as a biomarker for assessment of PAH pollution of the aquatic ecosystem. The main importance of the present study is in the combination of biochemical and chemical monitoring that provides complex evaluation of aquatic environment contamination. It was the first study on the Bílina River, in which the assessment of PAH contamination in the aquatic ecosystem was realized using combination of biotic and abiotic monitoring. PAH, 1-hydroxypyrene, SPMD, river pollution, biomonitoringThe environment is continuously loaded by allochtonous organic chemicals that have been produced and, in part, released into the environment by urban communities and industries. The ultimate destination of many of these contaminants is the aquatic environment, either via direct discharge or due to hydrological and atmospheric processes. One group of important ubiquitous environmental contaminants are polycyclic aromatic hydrocarbons (PAH) that are formed mainly by incomplete combustion of organic materials such as fossil fuels, industrial activities, smoked food, and smoked tobacco (Van der Oost et al. 2003).Many vertebrate aquatic organisms are able to metabolize and excrete PAH rapidly. Since the elimination of PAH is generally efficient in fish, no bioaccumulation of these compounds in fish has been proved. Concentrations of PAH in fish tissue are therefore not indicative of the concentrations to which the animals were exposed and cannot be used as biomarker for exposure assessment (Van der Oost et al. 2003). Fish absorb PAH through the gills and body surface but they can be also exposed through ingestion of food or contaminated sediment (Vuontisjarvi et al. 2004). The liver is the major organ involved in PAH metabolism, and the metabolites produced are secreted into ...