Exposure to a new wood preservative agent (Sinesto B), whose active ingredient is 2-ethylhexanoic acid (2-EHA), was determined by urinalysis of the parent chemical and its metabolites in workers employed in four Finnish sawmills. The excretion of these chemicals was compared with the inhaled dose analyzed in air samples collected at the breathing zone and with the percutaneous absorption determined by epicutaneous sampling. The main route for entrance of 2-EHA into the body is by breathing, because the urinary concentration of 2-EHA correlated linearly with the concentration of 2-EHA in the air (r = 0.70). There was no correlation between skin contamination and urinary levels of 2-EHA. In most cases the highest urinary concentrations of 2-EHA were found immediately after the work shift. Therefore, in order to evaluate a worker's exposure, the urine sample has to be taken immediately after the work shift. Workers in cranes had the highest exposure to 2-EHA, which describes well the evaporation of Sinesto B into the ambient air. 2-EHA was not found in the urine of non-exposed workers.