224 Background: Gemcitabine is a promising adjuvant treatment for patients with resected pancreatic adenocarcinoma. Human equilibrative nucleoside transporter 1 (hENT1) is the major transporter responsible for 2′, 2′-difluoro-2deoxycytidine (gemcitabine) uptake into cells. The aim of this study was to determine the outcomes according to the expression of hENT1 in tumor cells in patients treated with adjuvant gemcitabine chemotherapy after curative resection. Methods: We studied 27 pancreatic adenocarcinoma patients treated with gemcitabine adjuvant chemotherapy after curative resection and 8 gemcitabine naïve patients between 2006 and 2008. The hENT expressions were assessed using immunohistochemistry. The staining intensity of hENT1 protein was assigned a score from 0 to 3 based on staining with 0: no staining, 1: weakly positive, 2: moderately positive, 3: strongly positive. The percentage of positive tumor cells was scored as follows, 0: no positive tumor cell; 1: < 50% positive cells, 2: 51-80% positive cells, 3: > 81% positive cells. The hENT1 score was obtained by calculating the sum of these two scores. Each patients received adjuvant chemotherapy by either protocols as follows; GEM 1,000 mg/m2biweekly × 12 (6 months) or GEM 1,000 mg/m2Days 1,8,15; every 4 weeks for 6 months. Results: 11 patients were assigned to low hENT1 expression group (hENT1 score <4) and 16 patients to high hENT1 group (hENT1 score 4,5,6). The median DFS was 7.3 months (95% CI, 3.6-11.1) in the low hENT1 group, and 9.3 months (95% CI, 4.2-14.5) in the high hENT1 group. The median OS was 11.8 months (95% CI, 6.9- 16.6) in the low hENT1 group, and 22.2 months (95% CI, 11.5-32.9). The high hENT1 group had significantly longer DFS (Log-rank, p=0.04) and OS (p=0.02). In the gemcitabine naïve patients after curative resection, neither DFS nor OS correlated with hENT1 expression. Conclusions: In the pancreatic cancer patients treated with adjuvant gemcitabine chemotherapy after curative resection, both DFS and OS correlated with hENT1 expression. The expression of hENT1 may provides prognostic information and predictive for benefit from gemcitabine in these patients. No significant financial relationships to disclose.