In this study, we evaluated the clinical significance of detecting carcinoembryonic antigen (CEA) mRNA in the peripheral blood samples of patients with gastric cancer. We analyzed the peripheral blood of 46 patients with gastric cancer who had undergone curative resection. The presence of CEA mRNA was serially monitored using a CEA-specific reverse transcription-polymerase chain reaction (RT-PCR) every 2 months. The clinical recurrence rates according to category were as follows: 100% (3 of 3) in the positive conversion, 0% (0 of 18) in the negative conversion, 50% (3 of 6) in the always-positive, and 10.5% (2 of 19) in the always-negative category. The recurrence rate was 66.7% (6 of 9) in the positive group and 5.4% (2 of 37) in the negative group (P < or =0.00022). Multiple logistic regression analysis demonstrated that only group variable had a significant effect on clinical recurrence (P = 0.015). We conclude that RT-PCR analysis of CEA mRNA in the peripheral blood seems to be a promising tool for the early detection of micrometastatic circulating tumor cells in gastric carcinoma patients and that it can be useful used to identify patients at risk for recurring.