AIM: In this study, we aimed to investigate the roles of volume based 18F-FDG PET/CT parameters, CA19-9 levels, and complete blood count parameters in predicting survival in patients with unresectable and/or metastatic pancreatic ductal adenocarcinoma. MATERIALS AND METHOD: Fifty-seven pancreatic cancer patients who were followed in University of Health Sciences Gazi Yasargil Training and Research Hospital between January 2017 and June 2020, declined surgical treatment and/or radiation therapy or had medically inoperable, unresectable, or metastatic disease, and received chemotherapy were included in the study. 18F-FDG PET/CT images of patients were evaluated and calculated metabolic tumor volume (MTV) and total lesion glycolysis (TLG) parameters were compared with CA19-9 levels and complete blood count parameters. Patients were assessed in two groups as survivors and non-survivors. RESULTS: Total MTV and total TLG on 18F-FDG PET/CT were significantly higher among non-survivors than survivors (p: 0.023 and 0.034, respectively). Multivariate Cox regression analysis revealed that TLG higher than 46 g/ml.cm3 , MTV higher than 11.02 cm3 (OR 0.987, 95%CI 0.976-0.999, p:0.029 and OR 0.246, 95%CI 0.0890.685, p: 0.007, respectively) and elevated MPV (OR:0.785, 95% CI 0,574-0.976, p:0.042) were independent prognostic factors for predicting mortality. CONCLUSION: TLG >46 g/ml.cm3 and MTV >11.02 cm3 in 18F-FDG PET/CT and elevated MPV in complete blood count are independent prognostic factors for predicting mortality in patients with unresectable or metastatic pancreatic cancer who are treated with chemotherapy.