We report the malignant characteristics of circulating tumor cells (CTCs) and the corresponding molecular features of the primary tumor in a patient with esophageal squamous cell carcinoma (ESCC). A 70-year-old male patient was diagnosed with TNM stage T3N0M0 ESCC. Before surgery, seven intact CTCs and 12 CTCs with a fragmented membrane were detected in 7.5 mL of peripheral blood by immunofluorescence staining. One week after radical resection of the primary tumor, four CTCs were identified in 7.5ml peripheral blood. All CTCs were confirmed as having a malignant phenotype by chromosomal analysis and routine cell staining. Ninety percent of the CTCs were found to have polysomic chromosomes 8 and 20 by fluorescence in situ hybridization (FISH). Immunofluorescence analysis showed that all of the primary tumor cells detected were cytokeratin8/18/19 (CK8/18/19)-positive, but only 1% were CD133-positive. The serum CA19-9 and CEA level were normal in the process of diseases. The patient died 6 months after surgery as a result of lung metastases and other complications. The results of this study suggest that the dynamics and malignant characteristics of both CTCs and the corresponding primary tumor during the disease process may predict tumor burden and the risk of relapse and metastasis.