Our objectives were to test whether polymorphic variation in the (CAG)n repeat of the androgen receptor (AR) gene affects penetrance of germ-line BRCA mutations for ovarian cancer or age of diagnosis for ovarian cancer. Using a case-series study design, 179 consecutive Ashkenazi Jewish ovarian cancer patients were genotyped for AR repeat length and BRCA mutation status. There was no association between AR repeat length and presence of a BRCA mutation. However, ovarian cancer patients from both groups (with or without BRCA mutation) who carried a short AR allele were diagnosed an average of 7.2 (95% confidence interval, 2.3-12.1) years earlier than patients who did not carry a short allele (P = 0.004). These data suggest that AR allele length affects age of diagnosis of ovarian cancer, irrespective of BRCA mutation status.