Objectives. Pyrethroids are applied as insecticides throughout the world. Human metabolism of pyrethroids results in urinary metabolites that are suitable for biological monitoring. The aim of the study was to evaluate individual exposure due to occupational application of pyrethroids as a precondition for the assessment of health risks. Methods. Thirty-six workers who applied insecticides and other pesticides in Germany collected samples of their urine (24 h) after having used various pyrethroids (alpha-cypermethrin, cypermethrin, cyfluthrin, deltamethrin, tau-fluvalinate, permethrin, lambda-cyhalothrin) in agriculture, greenhouses or indoor pest control. Biological monitoring was carried out and metabolites were analysed in 61 urine samples by GC-MS: cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Cl(2)CA and trans-Cl(2)CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Br(2)CA), 3-phenoxybenzoic acid (3-PBA) and 4-fluoro-3-phenoxybenzoic acid (FPBA). Forty-five urine specimens collected (24 h) from persons with no occupational exposure to pyrethroids served as controls. Concentrations were related to creatinine content and expressed as microgrammes per gramme creatinine. Results. Control urine samples revealed a considerable background excretion of pyrethroid metabolites by the general population. The 95th percentile of the concentrations of Cl(2)CA and cis-Br(2)CA were 2.1 and 0.1 mug/g creatinine, respectively. FPBA was not detected in any control urine and was found in only one sample within the complete study. After occupational application of pyrethroids the highest concentrations of metabolites in urine samples were detected within the group of indoor pest-control operators. The maximum concentrations (median values) of Cl(2)CA, 3-PBA, and cis-Br(2)CA were 92.4 mug/g (1.8 mug/g), 57.5 mug/g (1.4 mug/g) and 1.1 mug/g (median below detection limit), respectively. Workers in greenhouses excreted metabolites with median concentrations as follows: 2.9 mug/g Cl(2)CA, 0.5 mug/g cis-Br(2)CA and 2.9 mug/g 3-PBA. Medians of the metabolite concentrations in specimens from agricultural workers were below the detection limit with regard to Cl(2)CA and cis-Br(2)CA, but the value was 0.6 mug/g for 3-PBA. Pest-control operators excreted significantly higher concentrations of Cl(2)CA and 3-PBA than workers in agriculture on a collective basis. Comparison of the excreted concentrations of metabolites with values of acceptable daily intake (ADI) of pyrethroids set by WHO revealed that the amount of pyrethroids that had been taken up during occupational application was not considerably higher than the ADI. Conclusions. As a consequence, we conclude that adverse health effects are not to be expected after workers' occupational exposure to pyrethroids in Germany, provided that the application is carried out properly. Good working practices need to be supported by adequate supervision with regard to occupational hygiene and medicine.