The cytoplasmic enzyme dihydrodiol dehydrogenase (DDH) plays an important role in detoxification. Patients with DDH overexpression have a significantly higher incidence of early tumor recurrence and distant metastasis. This study evaluated the correlation between clinicopathological data and DDH expression and the prognostic significance of DDH expression in patients with resected gastric cancer. Between January 1998 and September 2004, we retrospectively enrolled 81 patients who received surgical treatment for gastric cancer. Pathology samples were immunostained with monoclonal antibody to DDH. The relationship between DDH expression and clinicopathological data (age, gender, histological type, stage) was analyzed by chi-square analysis. Survival curves were plotted using the Kaplan-Meier method and compared using a log-rank test. The overexpression rate of DDH was 41.9%. Of patients with overexpressed DDH, 13% had stage I, 24% had stage II, 52% had stage III, and 78% had stage IV tumors. Among patients who died, DDH expression level differed significantly between high and low-expression groups (P = 0.042). Survival was significantly better in patients with low DDH expression (P = 0.048). Thus, DDH expression may be useful in identifying high-risk gastric cancer patients and distinguishing future candidates for curative and palliative treatment.