BACKGROUND We evaluated the influence of several clinicopathologic variables on 5-year actuarial survival rate after curative resection of gastric adenocarcinoma. METHODS Clinical characteristics were retrieved from the records of all patients who underwent gastric resection for curative intent between 1965 and 1986 at The University of Chicago Medical Center, and follow-up was obtained from our tumor registry. Pathologic characteristics were determined from a detailed review of all available histopathologic slides. RESULTS One hundred seventy-eight patients underwent a curative resection during the study period at our institution. Overall 5-year actuarial survival rate was 29%. The relationship between clinicopathologic variables and 5-year survival rate was evaluated by Kaplan-Meier survival curve construction and chi-squared analysis. Lymphatic and/or capillary microinvasion (absent vs present, p < 0.001), tumor location (antrum and body vs gastroesophageal junction, p = 0.05), local extent of disease (limited to the gastric wall versus involving adjacent organs, p = 0.003), stage (absence versus presence of lymph node metastases, p < 0.001), Lauren type (intestinal versus diffuse, p < 0.01), and Ming type (expanding versus infiltrative, p < 0.02) significantly influenced survival. When a multivariate analysis with logistic regression of 5-year survival was performed, lymphatic and/or capillary microinvasion emerged as the only statistically significant, independent prognostic factor associated with long-term survival (p = 0.039). If microinvasion was omitted from the analysis, lymph node metastases (p < 0.05) and the extension to adjacent organs (p < 0.04) became the only statistically significant variables. Multiple correlation analyses suggested that microinvasion is an early histopathologic finding that correlates with a more aggressive natural history. CONCLUSIONS Lymphatic and/or capillary microinvasion is a more powerful predictor of 5-year survival than lymph node metastases or tumor extension to adjacent organs. Correlation among clinicopathologic variables suggests that microinvasion may represent an early finding, serving as a potential marker for a biologically more aggressive tumor.