Abstract: Objective: To investigate the expression of CK- 19 in the resected lymph nodes of esophageal carcinoma patients using FITC- labeled flow cytometry and to analyze the correlation between lymph node micrometastasis and prognosis. Methods: The CK-19 gene is expressed in esophageal epithelium and it is not expressed in normal lymph nodes. A total of l00 patients were selected randomly from those who underwent radical surgery for esophageal carcinoma from January 1998 to December 1999, and 1248 lymph nodes were collected from these patients to be assessed for CK- 19 expression by flow cytometry. Results: Two hundred and seventy- nine lymph nodes were confirmed to contain metastasis by both routine pathology and FITC- labeled flow cytometry. The other 969 lymph nodes without metastasis according to pathology were retested with FITC- labeled flow cytometry. Based upon the flow cytometry data, 156 lymph nodes from 28 patients showed micrometastasis(MM). The mi-crometastatic rate was 41.8%, and the micrometastatic degree was 16.1%. The 1-, 3-, and 5- year survival rates in MM(+) patients were 82.1%, 53.6%, and 14.3%, respectively. Micrometastasis was correlated with tumor cell differentiation and infiltrative depth of the tumor, and it was not correlated with age, gender distribution, and tumor stage. Lymph node micrometastasis was correlated with prognosis. Conclusion: Micrometastases, which cannot be detected microscopically, exist in the lymph nodes in the region of esophageal carcinoma. The poor prognosis of some patients without microscopically de-tectable metastasis was attributable to micrometastasis. We suggest that the detection of micrometastasis by FITC- labeled flow cytometry should be a standard procedure so that those patients with micrometas-tasis can receive proper treatment.