Background: The superiority of FOLFIRINOX (FFX) therapy over gemcitabine (Gem) alone in patients with metastatic pancreatic cancer (mPC) has been demonstrated in ACCORD11. However, this combination regimen is associated with relevant toxicity and predictors for response to therapy are warranted. The aim of this study is to determine the prognostic factors associated with an indication for FFX therapy in patients with mPC. Methods: The current study included data from all consecutive patients who were diagnosed as mPC at our hospital between September 2007 and December 2014. Selection criteria were as follows: patients who 1) had histologically confirmed pancreatic adenocarcinoma, 2) were diagnosed as having metastatic disease, and 3) received first-line chemotherapy with Gem alone or FFX. We examined the prognostic markers, such as derived neutrophil–lymphocyte ratio, platelet–lymphocyte ratio, modified Glasgow prognostic scale (mGPS), ECOG Performance Status (PS), CA19-9 level and number of metastatic sites from the medical records and analyzed their survival data by chemotherapy regimen subgroups. Results: There were 187 patients who met the selection criteria. 159 (85%) received Gem alone, 28 (15%) received FFX. Univariate and multivariate regression analyses revealed that mGPS (1≦), number of metastatic sites (2≦) and high level of CA19-9 level (1000 U/ml≦) were significantly associated with worse prognosis in Gem group. PS (1≦) and mGPS (1≦) were significantly associated with worse prognosis in FFX group. Since mGPS was the only significant prognostic marker in both groups, we analyzed survival data stratified by regimen in both mGPS 0 or 1≦ cohort. In mGPS 0 cohort, the median survival time was 17.9 months in the FFX group as compared with 8.5 months in the Gem group (hazard ratio, 0.27; 95% CI, 0.11 to 0.55; P = 0.004). However there was no significant difference in mGPS 1≦ cohort (P = 0.4). Conclusions: This data suggests that mGPS 0 is associated with better survival time, and suggests it may also be predictive of benefit for FFX in Japanese patients with mPC. Incorporating mGPS into the clinical context may better inform prognosis and chemotherapy decisions in mPC patients.