We report a case of small cell lung cancer with anti-Hu antibody-positive paraneoplastic neurologic syndrome preceded by variable neurological symptoms. A 57-year-old man first noticed a numbness on the inner side of his right leg in April 1998. He was later admitted to a hospital following the development of polyneuropathy, cerebellar dysfunction, and psychological symptoms. Chest plain X-ray films and computed tomographic scans disclosed a mass shadow in the right upper lobe, in addition to enlarged mediastinal lymph nodes. Small cell lung cancer was suspected on the basis of pathologic findings on an enlarged right supraclavicular lymph node and radiologic findings. The patient was referred to our hospital in October 1998. Anti-Hu antibody was detected both in serum and cerebrospinal fluid. Small cell lung cancer (clinical T1N3M0, stage IIIB) with paraneoplastic neurologic syndrome was diagnosed. Three courses of combination chemotherapy (carboplatin and etoposide) were administered with a partial response. However, the patient's neurological symptoms were not alleviated. We discussed the mechanism, clinical symptoms, and treatment of this disease.