Background: TAS-118 is a novel oral agent, containing S-1 and leucovorin. In the SOLAR study (NCT02322593), TAS-118 + oxaliplatin (OHP) significantly improved overall survival compared to S-1 + cisplatin for patients (pts) with advanced gastric cancer (GC). We conducted this open-label study to assess feasibility of perioperative adjuvant chemotherapy with TAS-118 + OHP in pts with locally advanced resectable GC with lymph node metastasis. (Clinical trial information: UMIN000024688). Methods: Eligible pts who had histopathologically confirmed GC with clinical T3-4N1-3M0 on image findings (14^th Japanese classification of gastric carcinoma), age 20 to 79 years, were enrolled in this study. The protocol treatment consisted of preoperative 4 courses of TAS-118 (80-120 mg/body, days 1-7) + OHP (85 mg/m², day 1) every 2 weeks, and gastrectomy with D2 lymphadenectomy, followed by postoperative 12 courses of TAS-118 alone (step1) or 8 cycles of TAS-118 + OHP (step2). The primary endpoints were tolerability of preoperative chemotherapy, gastrectomy and postoperative chemotherapy with TAS-118 plus OHP. Here, we report the feasibility of preoperative chemotherapy and gastrectomy, and pathological response. Results: Between December 2016 and April 2018, 45 pts with a median age of 61 years were enrolled. The numbers of pts with T stage (cT3/4a) and those with N stage (cN1/2/3) were 13/32 and 25/17/3, respectively. The completion rate of preoperative chemotherapy and gastrectomy was 88.9% ( 95% CI 78.0-95.5) and 95.6% (95% CI 86.7-99.2). The relative dose intensity of TAS-118 and OHP was 86.0% and 90.6%. During the 4 cycles of preoperative TAS-118 + OHP, 2 pts discontinued the treatment due to adverse event (AE). Major grade 3-4 AEs were diarrhea (17.8%) and neutropenia (8.9%). R0 resection rate was as high as 95.6%. One pts experienced grade 4 postoperative bleeding, but no treatment-related death was reported. pCR was achieved in 6/45 pts (13.3%) and other 7 pts (28.9%) showed near complete regression (<10 % residual tumor cells). Conclusions: Preoperative TAS-118 + OHP followed by D2 gastorectomy was well tolerated and showed promising efficacy. Clinical trial information: 000024688.