Purpose: Alpha-fetoprotein (AFP) is widely accepted as a useful tumor marker for diagnosis of hepatocellular carcinomas. On rare occasions, however, an abnormal elevation of serum AFP also has been reported in an adenocarcinoma of the gastrointestinal tract. We evaluated the influence of preoperative abnormal elevation of serum AFP (AFP positivity) on the prognosis of resectable gastric cancers. Materials and Methods: 812 gastric cancer patients, who were investigated for serum AFP before their operations and who underwent gastric resections with D2 or more extended lymph node dissection, were enrolled in the study. The survival rates were calculated by using the Kaplan-Meier method and were compared by using the log-rank test. A multivariate analysis was performed using the Cox proportional hazards model. Results: Fifty patients ($6.2\%$) were AFP positive (10.1. 4322.6 ng/ml). The survival rate of the AFP positive group was significantly lower than that of the AFP negative group ( $46.6\%;vs.;67.0\%$; P=0.0002). The depth of tumor invasion, the degree of regional lymph node metastasis, distant metastases, the TNM stage, the gross type, differentiation, the extent of gastric resection, and the curability of the surgery also significantly influenced survival. Multivariate analysis revealed that the depth of tumor invasion, the degree of regional lymph node metastasis, the curability of the surgery, and AFP positivity were independent prognostic indicators. Conclusion: Preoperative serum AFP can be used as an independent prognostic factor of resectable gastric cancer.