Although endometrial BRCA2 mRNA expression was comparable in both groups (2.19 ± 0.59 vs. 9.86 ± 3.02; p = 0.051), levels of BRCA1, Rad51, and ATM were significantly lower in endometriosis group, compared with controls [0.25 ± 0.03 vs. 0.54 ± 0.11 (p = 0.014); 4.95 ± 1.11 vs. 11.77 ± 3.05 (p = 0.024); and 0.25 ± 0.03 vs. 0.545 ± 0.11 (p = 0.016), respectively]. This evidence concerns the gene RAD51 and endometriosis.