EROD activity was identified in 82% of clear-cell renal carcinomas (n=19/23) (65–992 fmol min mg−1 of microsomal protein) with similar levels of CYP1B1 activity also demonstrated in the chromophobe (n=2) and papillary renal carcinomas (n=1). This evidence concerns the gene CYP1B1 and clear cell renal carcinoma.