4581 Background: The main treatment of Gastric Carcinoma(GC) is Surgery, but 5 years recurrence risk is 70% and mortality 50%. So that, effective adyuvant therapy, like chemotherapy, is needed to impact on survival ; results, however have been inconsistent at best. Inmunotherapy with interferon alpha, in gastric carcinoma, has only been employed in metastatic disease. The objective of this study was evaluate chemoimmmunotherapy role of interferon alpha - 2b,5-FU and LCV as adjuvant therapy in GC Methods: This is a randomized prospective study. Beginning 2/Oct /97 and finalizing 31/march/2005. Patiens with gastric adenocarcinoma, clinical stages II, III and non metastatic IV, after gastrectomy, without cancer antecedent were included. Treatment groups were assigned at random: Group A: 5-FU: 400 mg/m 2 , days (1–3), leucovorin: 50 mg. days (1–3), interferon alpha - 2b: 5x10^6 units sq, every other day, days (1–15). Group B: 5-FU, LCV without interferon alpha, at the same doses. Nine (9) monthly cycles were aplied. Clinical and paraclinical follow up was made appropriately. Statistic analysis was performed by Kaplan Meier method. Results: 52 patients were studied, 25 in group A and 27 in group B. Both of them had similar characteristics in median age, sex, histology, differentiation grade, gastric location, clinical stage: A: II: 28%, III: 72% (IIIB: 56%). B: II: 29,6%, III: 70% (IIIB: 55%).General survival (SG) analysis: Mean SG (%): A: 64%. B: 18,5%. Mean SG (months): A: 68,5 m. (CI 95%: 59–78,15). B: 27,98 ( CI 95%: 18,92–37,04). Survival curves comparison, minimum until 5 years: Log Rank, Breslow, Tarone Ware: P<0,00001, all of them in favor to group A. Mortality: Total:31/52: 59,6%. A: 36%. B: 81,48% (P<0,05). Disease free survival (DFS) analysis: Mean DFS (%): A: 52%. B: 18, 52%. Mean DFS(months): A: 58,85m (CI 95%: 47,4–70.3). B: 24,98m (CI 95 %: 15,3–34.6). DFS curves comparison: Log Rank: 0,0008. Breslow: 0,0003. Tarone Ware: 0,0004. All of them in favor to group A. Recurrence (%): Total: 34/52:65%. A: 48%. B: 81,48% ( P <0,05). Conclusions: This is the first study of adjuvant chemoimmunotherapy (CI) that includes interferon alpha - 2b in GC. This study shows CI with 5-FU, LCV and interferon alpha -2b is effective as adjuvant treatment in GC. No significant financial relationships to disclose.