In this study of common and coding variation in 3 sex hormone receptors (ESR1, ESR2, PGR) and 5 hormone-synthesizing enzymes (CYP17A1, CYP19A1, HSD17B1, HSD17B2, HSD17B4) in relation to colorectal cancer risk among WHI-OS women of European ancestry, we observed suggestive evidence for an association with the rs17724534 SNP in CYP17A1. The association with colorectal cancer was more pronounced when the risk attributable to this SNP was combined with that of another SNP (rs10883782) in the same gene. This evidence concerns the gene HSD17B4 and colorectal cancer.