Nine workers occupationally exposed to styrene producing refrigerator lorries were analyzed. The styrene exposure was monitored 8 hours a day, for 5 days a week, for 1 week. We collected from workers a urine sample before and after each work shift. Moreover, alveolar air samples were obtained at the end of all work shifts. On Thursday afternoon and on Friday morning blood samples were taken from workers. The relationship between styrene exposure and biological data is reported and discussed. Alveolar, urinary and blood concentrations of styrene were comparable, suggesting similar kinetics. Biological styrene concentrations were significantly correlated with the mean daily environmental concentrations, but higher correlation coefficients were found with afternoon exposures. A narrow linear relationship between alveolar (Y) and urinary (X) styrene concentrations was found (Y = 0.359; r = 0.8579; n = 45; p less than 0.001). Urinary concentrations of mandelic acid (Y) confirmed a good relationship with the mean styrene exposure (X) (Y = 2.7 x +169; r = 0.4677 n = 45; p less than 0.01).