Published data on the association between STK15 F31I polymorphism and breast cancer risk are inconclusive. In order to derive a more precise estimation of the relationship, a meta-analysis was performed. Medline, PubMed, Embase, Web of Science, and Chinese Biomedicine Database were searched. Crude ORs with 95% CIs were used to assess the strength of association between the STK15 F31I polymorphism and breast cancer risk. The pooled ORs were performed for codominant model (FI vs. FF; II vs. FF), dominant model (FI + II vs. FF), and recessive model (II vs. FI + FF), respectively. A total of 10 studies including 10,537 cases and 14,477 controls were involved in this meta-analysis. Overall, significantly elevated breast cancer risk was associated with II variant genotype in homozygote comparison and recessive genetic model when all studies were pooled into the meta-analysis (for II vs. FF: OR = 1.23, 95% CI = 1.10-1.37; for recessive model: OR = 1.21, 95% CI = 1.05-1.40). In the subgroup analysis by ethnicity, significantly increased risks were found for II allele carriers among Caucasians (for II vs. FF: OR = 1.24, 95% CI = 1.08-1.43; for recessive model: OR = 1.21, 95% CI = 1.00-1.45); significantly increased risks were also found among Asians for II versus FF (OR = 1.21; 95% CI = 1.01-1.45). In conclusion, this meta-analysis suggests that the STK15 31II allele is a low-penetrant risk factor for developing breast cancer. © 2009 Springer Science+Business Media, LLC.