Mercury levels in air, urine, blood, and hair were studied for workers (14 women, 2 men, ages 18-44 a) employed in a small thermometer factory (metallic mercury vapor exposures) with generally inadequate engineering and hygienic arrangements. At exposure levels of 50-99 microgram/m3 (5 workers), 100-149 microgram/m3 (3 workers) and 150-200 microgram/m3 (7 workers), respectively, the mean mercury levels were 299, 449 and 628 nmol/l in urine; 105, 122 and 143 nmol/l in blood, and 4.2, 8.5 and 12.2 mumol/kg in hair (1 cm from base). Headache, irritability-hair loss, and wrist and ankle pain were the most frequently occurring symptoms. The correlation coefficients between the measured mercury levels in air for individual workers and mercury in urine, blood, and hair (1 cm from base) were r = 0.92, r = 0.79, and r = 0.42, respectively. Mercury determinations for segmental hair cuts indicated peaks and drops in absorption/deposition consistent with data on the vacations of the individual mercury levels of 150-770 nmol/l may be helpful when current thresholds of exposure/absorption are reconsidered.