Coke oven workers are exposed to high concentrations of polycyclic aromatic hydrocarbons. Only recently have methods been developed to try to assess the individual, biologically significant exposure. The only coke oven plant in Finland started to function in 1987, in Raahe, enabling the implementation of a cohort study among the workers to determine the usefulness of some currently available biomonitoring methods, e.g. methods of measuring PAH-DNA adducts. Urine and blood samples were taken several times from a sample of workers starting from before they worked at the plant. A questionnaire (smoking, diet, former and current occupations) was filled in by the workers at every sampling, and air samples (personal and stationary) were collected at the same time. The mean values of both benzo(a)pyrene diolepoxide (BPDE)-DNA adducts were measured by synchronous fluorescence spectrophotometry (SFS) and the antibodies to these adducts increased somewhat after the work at the plant started. However, all the adduct values were low, and no differences between the smokers and non-smokers at any time point were detected. Battery workers had slightly increased means of BPDE-DNA adducts compared to non-battery workers. Also, coke oven workers had slightly higher adduct values than age, sex and smoking matched controls.