Objectives: We report one patient with pleural effusion and effusion-related symptoms in small cell lung cancer (SCLC) successfully treated with Gunreyngtang-gagambang. Methods: Gunreyngtang-gagambang was administered at 30 minutes after mealtime, three times a day, for two months. Except for herbal medicine, the patient did not take any treatment including pharmaceutical or non pharmaceutical for effusion. Result: Two months later, the symptoms and the pleural effusion had disappeared from chest X-ray. Conclusion: Gunreyngtang-gagambang was effective for treatment of malignant pleural effusion due to small cell lung cancer.