The exposure of fire-fighting trainers to polycyclic aromatic hydrocarbons (PAH) was assessed by personal air sampling. Uptake of PAH was determined by biological monitoring, measuring a metabolite of pyrene, 1-hydroxypyrene, in urine. Eight-hour time-weighted average concentrations benzo(a)pyrene of 0.029 microgram/m3 (instructor), 0.045 microgram/m3 (safety officer), and 0.16 microgram/m3 (fire assistant) were found. Both tobacco smoking and exposure to smoke from fire appeared to be significant sources of increased 1-hydroxypyrene concentrations in fire-fighting trainers. There was evidence of exposure and uptake of PAH among fire-fighting instructors despite the short time of effective exposure and the routine use of protective respirators and protective clothing. Though the uptake of PAH was much lower than found in coke-oven workers, who are known to have an increased relative risk of cancer, a long-term health risk for fire-fighting trainers cannot be excluded. Biological monitoring with urinary 1-hydroxypyrene may be useful in tracing highly exposed persons and in monitoring the effectiveness of control measures.