Ten men occupationally exposed to styrene in two glass-fiber reinforced plastics factories were studied during three consecutive workdays. The mean external exposure level was 99 mg/m3. The total pulmonary uptake of styrene was estimated from measurements of the styrene concentration in inspired air, the pulmonary ventilation, and the relative uptake. A gas chromatographic method based on electron capture detection was used to quantify styrene glycol, as well as styrene-7,8-oxide, in blood. The concentration of styrene glycol appeared to be linearly related to the preceding uptake of styrene. When the uptake during 5 h immediately before the blood sampling was considered, the correlation coefficient (r) obtained the value of 0.90. The concentration of styrene-7,8-oxide was at the detection limit of 0.02 mumol/l in most samples. A weaker correlation between the concentration of styrene in blood and the uptake during the hour immediately preceding the blood sampling was obtained (r = 0.71).