We observed that individuals occupationally exposed to solvents with at least one low activity GSTA1 allele had the highest risk (about 9 times), while GSTM1-null carriers had 6.5 times higher bladder cancer risk when compared to unexposed GSTA1 AA and GSTM1-active persons, respectively. This evidence concerns the gene GSTM1 and urinary bladder carcinoma.