We describe herein the case of a 68-year-old man who experienced leptomeningitis after esophagectomy from an esophageal basaloid carcinoma. Although the patient had a good operative course for the first 10 days after surgery, he suddenly had general convulsions with unconsciousness. He was placed on mechanical ventilation in an intensive care unit. Computed tomography and magnetic imaging resonance did not reveal any abnormal findings. No abnormal data in the cerebrospinal fluid were found by biochemical, virological, and cytological examination. The positive expression of carcinoembryonic antigen messenger ribonucleic acid in cerebrospinal fluid was detected by a quantitative reverse transcription-polymerase chain reaction method. Immunohistochemical staining using an anticytokeratin antibody confirmed the presence of tumor cells in the cerebrospinal fluid. Spontaneous breathing was recovered after treatment with systemic chemotherapy. Six months after surgery, computed tomography revealed multiple brain metastases. This case demonstrates that the quantitative reverse transcription-polymerase chain reaction method of analyzing carcinoembryonic antigen messenger ribonucleic acid may be a sensitive and useful method for determining leptomeningeal metastasis before the detection of tumors by cytological and imaging examinations in patients with cancer.