Though previous studies investigated the association between glutathione S-transferase M 1 (GSTM1) null genotype and ovarian cancer risk, the effect of GSTM1 null genotype on ovarian cancer risk was still unclear. To comprehensively quantify the association between GSTM1 null genotype and ovarian cancer risk, we performed a meta-analysis. Eleven studies from ten publications were identified from PubMed database. The pooled odds ratio (OR) with its 95% confidence interval (CI) was used to assess the association. Meta-analysis of the total 11 studies showed that GSTM1 null genotype was not associated with ovarian cancer risk (OR = 1.03, 95% CI 0.92-1.14, P = 0.625). The cumulative meta-analyses showed a trend of no association between GSTM1 null genotype and ovarian cancer risk as information accumulated by year. There was no evidence of publication bias in the meta-analysis. Meta-analysis of the 11 available studies shows that GSTM1 null genotype is not associated with ovarian cancer risk.