We did not observe a significant association between the NQO1 Pro187Ser polymorphism and breast cancer risk when all studies were pooled into the meta-analysis (Ser/Ser vs. Pro/Pro: OR = 1.251, 95% CI 0.843–1.856, P = 0.266; Ser/Pro vs. Pro/Pro: OR = 1.015, 95% CI 0.860–1.198, P = 0.860; Ser/Ser + Ser/Pro vs. Pro/Pro: OR = 1.058, 95% CI 0.899–1.245, P = 0.498; Ser/Ser vs. Ser/Pro + Pro/Pro: OR = 1.317, 95% CI 0.919–1.887, P = 0.133). Here, NQO1 is linked to breast cancer.