The aim of the present study was to evaluate whether aluminum exposure may cause alterations of cytochrome P4503A4 by measuring the urinary excretion of 6 beta-hydroxycortisol as biomarker. There is a positive correlation between urinary 6 beta-hydroxycortisol and aluminum excretion (p < 0.05). The correlations between occupational duration, smoking habits, and age were also evaluated. The increased excretion of the biomarker suggests that this element may induce formation of cytochrome P 450 in exposed individuals.