We encountered a case of small-cell lung cancer in a patient with subacute sensory neuropathy that began 5 months before the cancer was diagnosed. A 60-year-old man complained of abnormalities in the functioning of his peripheral sensory systems (senses of pain, touch, position, and vibration). A chest X-ray film obtained on admission showed an anterior mediastinal tumor. The anti-Hu antibody was found in his serum. The diagnosis was small-cell lung cancer. Combination chemotherapy (cisplatin and irinotecan, CPT-11) was begun and the response was a complete remission. The symptoms of neuropathy continued. The anti-Hu antibody was useful in the diagnosis in the case of small-cell lung cancer combined with subacute sensory neuropathy.