A simple capillary gas chromatographic method is described for direct determination of styrene-7,8-oxide (styrene oxide) in blood samples of 1 ml, with a detection limit of 1 ng/ml. After the addition of 1-phenylpropylene oxide as internal standard, blood samples were extracted with n-hexane, the n-hexane phases were concentrated under nitrogen, and up to 25 μl of the resulting solution were injected on-column using a retention gap. Separation was carried out on a fused-silica capillary column coupled to a flame ionization detector. Using this method the metabolism of styrene oxide in rat blood was investigated. Concentrations of styrene oxide in the blood of rats exposed to styrene at atmospheric concentrations between 20 and 800 ppm for 3 h at steady-state conditions are reported.