A 67-year-old man was admitted with left pleural effusion on chest X-ray film. Chest CT scans showed an anterior mediastinal tumor, left pleural dissemination and pleural effusion. Percutaneous needle biopsy yielded a diagnosis of epitherial carcinoma. The patient underwent 3 courses of systemic chemotherapy (CDDP + ADM + VCR + CPA). At achievement of partial response, the tumor was completely resected. Examination of the resected tumor revealed partial response to chemotherapy. A 49-year-old woman was admitted our hospital with supraclavicular lymph nodes swelling. Chest CT scans showed an large mediastinal tumor. Percutaneous needle biopsy yielded a diagnosis of squamous cell carcinoma of thymus. The patient underwent 3 courses of systemic chemotherapy. At achievement of partial response, the tumor was completely resected. Examination of the resected tumor revealed partial response to chemotherapy. These cases indicate the usefulness of preoperative chemotherapy for advanced thymic carcinoma to reduce tumor size and to control local invasion, distant metastasis before operation.