Background: Gemcitabine (GEM) plus nab-paclitaxel (nP) are one of the standard of care for metastatic pancreatic cancer, but it is still controversial about the value in non-metastatic patients. Purpose: The primary objective of this study is to assess the toxicity of concurrent chemoradiotherapy (CRT) with a combination of GEM and nP for unresectable locally advanced pancreatic cancer (UR-LAPC). Methods: Chemotherapy-naive patients with histologically or cytologically proven UR-LAPC were enrolled to this trial. The patients received GEM and nP intravenously over 30 min. respectively on days 1, 8 and 15 every 28 days. Cycles were repeated every 28 days during radiotherapy. Patients were scheduled to receive GEM (mg/msq/week) and nP (mg/msq/day) at six dose levels: 600/50 (level 1), 600/75 (level 2), 600/100 (level 3), 800/100 (level 4), 1,000/100(level 5) and 1,000/125(level 6). Radiation therapy was delivered through four fields as a total dose of 50.4 Gy in 28 fractions over 5.5 weeks, and no prophylactic nodal irradiation was given. Dose-limiting toxicity (DLT) was defined as grade 4 hematological toxicity, grade 3 non-hematological toxicity and >14 days delay of treatment. Every patients were evaluated for response with RECIST criteria. Results: Twenty one patients were enrolled in this study between 12/2013 and 05/2015. Treatment was well tolerated; Every 21 patients completed radiotherapy of 50.4 Gy. Our recommended dose was level 3, Gem 600mg/ nP 100mg. Nine patients experienced DLT. The response rate was 67% (CR 0, PR 14, SD 6 and PD 1). Median OS was 23.8 months (95%CI: 17.0, -) and median PFS was 9.0 months (95%CI: 4.8, 11.9). Conclusions: The CRT with a combination of GEM and nP can be delivered almost safely for UR-LAPC. Clinical trial information: UMIN000012254.