Background: Many studies have investigated the association between the MDM2 promoter SNP309 T/G polymorphism and liver cancer risk, but inconsistencies make drawwing definitive conclusions difficult. Methods: We therefore searched main databases for articles relating MDM2 SNP309 T/G polymorphism to risk of liver cancer in humans and estimated summary odds ratio (OR) with 95% confidence intervals (95% CI) to assess the possible association in a meta-analysis. Results: The main analysis revealed no significant heterogeneity, and the pooled ORs of fixed-effects were all significant (for G versus T, OR = 1.59, 95% CI 1.42-1.78; for GG versus TT, OR = 2.45, 95% CI 1.93-3.12; for GT versus TT, OR = 1.70, 95% CI 1.38-2.09; for GG versus GT, OR = 1.49, 95% CI 1.24-1.79; for GG and GT versus TT, OR = 1.95, 95% CI 1.61-2.38; for GG versus TT and GT, OR = 1.73, 95% CI 1.46-2.07). Subgroup analyses by ethnicity and sensitivity analyses both showed associations to remain significant. Conclusion: The present meta-analysis of available data showed a significant association between the MDM2 SNP309 T/G polymorphism and liver cancer risk, the MDM2 SNP309 G allele contributing to increased risk in both Asians and Caucasians in a graded, dose-dependent fashion.