BACKGROUND: High Neutrophil/Lymphocyte ratio (NLR), as a measure of enhanced inflammatory response, has been negatively associated with prognosis in patients with localized pancreatic ductal adenocarcinoma (PDA). OBJECTIVE: In the present study, we aimed at investigating the prognostic value of NLR in two homogeneous groups of chemotherapy-na've metastatic PDA patients. Patients were treated with either gemcitabine (GEM) or gemcitabine/ oxaliplatin (GEMOXA). We also assessed whether NLR could identify patients benefiting from the use of oxaliplatin. METHODS: Consecutive PDA patients treated at the Medical Oncology Unit of Tor Vergata University Hospital of Rome with either GEM or GEMOXA were included (n = 103). NLR was assessed before and during chemotherapy and correlated with outcome together with common clinical and biochemical variables. RESULTS: Among 17 analyzed variables NLR, Karhofsky Perfomance Status (KPS), d-dimer and erythrocyte sedimentation rate were found to be significantly associated with median Overall Survival (mOS) at the univariate analysis. Only NLR and KPS were independent prognosticator at multivariate analysis, with NLR displaying the highest statistical significance. NLR was also predictive of oxaliplatin activity, as only patients with NLR > 2.5 (cutoff determined upon ROC analysis) derived benefit from GEMOXA over GEM. CONCLUSIONS: NLR is both an independent prognostic and predictive factor in metastatic PDA, since only patients with high NLR seem to benefit from the addition of oxaliplatin. NLR may help select patients for whom a particularly poor prognosis might justify more intensive, yet less tolerable, combination regimens.