FOLFIRINOX is a highly active regimen for the treatment of patients with unresectable pancreatic cancer. However, treatment with FOLFIRINOX is associated with relevant toxicity and predictors for response to therapy are warranted. We retrospectively analyzed 49 patients with unresectable pancreatic cancer treated with FOLFIRINOX in order to evaluate a possible predictive role of clinical parameters and tumor characteristics for response to chemotherapy. Tumor samples were characterized histopathologically before treatment and expression of p53 and Ki67 was analyzed using automated immunohistochemistry. Overall survival (OS) and progression-free survival (PFS) were estimated by the Kaplan-Meier method. The overall objective response rate was 55.1%, the disease control rate was 70.6%. Female gender was associated with a significantly higher disease control rate of 91.7 compared to 48.0% in male patients (p=0.001) which reached 100% in female patients when primarily treated compared to treatment after surgical resection and relapse (77.8%, p=0.057). For all patients median PFS was 3.5 months (95% CI, 2.7-4.3 months) and median OS was 13 months (95% CI, 9.4-16.6 months). Female patients showed a tendency towards a longer median PFS (5.0 months, 95% CI, 3.6-6.4 months) compared to males (3.0 months, 95% CI, 2.4-3.6 months) (p=0.099). Serum levels of CA19.9 and CEA were significantly higher in female patients compared to male patients (p=0.037, p=0.05). Tumors of patients with response to FOLFIRINOX showed a higher expression level of p53 and Ki67 as well as higher serum levels of CA19.9 compared to non-responders, which was statistically not significant. Our study indicates that female gender is a positive predictor for therapy response to FOLFIRINOX in patients with unresectable pancreatic cancer. Female gender in turn was associated with increased levels of tumor markers CEA and CA19.9 and patients with higher serum levels of CA19.9 were more responsive to FOLFIRINOX.