Exposure to PAH in foundry workers has been studied by urinary 1-hydroxypyrene (HPU) levels, quantitatively measured by reversed phase HPLC. Seventy male foundry workers and 68 matched controls were investigated. Polycyclic aromatic hydrocarbon (PAH) exposure was defined by 17 breathing zone hygienic samples, consisting of 16 selected PAH compounds. Mean total PAH concentration (SD) was 10.40 (4.04) mu g/m3. A multiple regression model of tobacco consumption, age, airborne PAH-exposure and foundry work on log HPU showed a significant correlation, p <0.001, r2 = 0.69. Only foundry work (p <0.0001) and airborne PAH exposure (p = 0.0478) contributed significantly to the model. These data suggest that HPU is a sensitive biomarker for low-dose PAH exposure.