Ovarian cancer is an aggressive disease with high mortality. The CXCL12 chemokine has been associated with the development of this neoplasia. The aim of this study was to evaluate the genetic influence of the CXCL12-3'A polymorphism as a prognostic/predictive factor in ovarian cancer patients treated with platinum/paclitaxel chemotherapy. The mean survival rates for early stages (I/II) of the disease were statistically different according to patient genotype (96 months for GG and 57 months for A carrier genotypes; p=0.017). The mean progression-free interval was statistically lower in patients with early stages (I/II) of the tumour carrying the A allele (55 months) than in those carrying the GG genotype (91 months; P=0.009). The CXCL12-3'A polymorphism leads to a poorer response to chemotherapy with cisplatin/paclitaxel, and diminishes the mean survival rate and the progression-free interval in patients with ovarian cancer. CXCL12-3'A may therefore serve as an important predictive biomarker for the determination of outcome in ovarian cancer.