We report a case of Castleman's disease which developed in the posterior mediastinum, with a review of the Japanese literature. A 19-year-old female patient with asthma was pointed out to have an abnormal shadow in the right posterior mediastinum on chest X-ray. We had tried to perform thoracoscopic surgery for this tumor, but we had to convert the surgical approach from thoracoscopy to a thoracotomy because of both tight adhesion of the tumor and muscle and profuse bleeding from the tumor. The tumor was diagnosed to be the hyaline vascular type of Castleman's disease histopathologically. In the Japanese literature, Castleman's disease, which develops in the posterior mediastinum, has been reported to often accompany tight adhesion between the tumor and surrounding tissue, and profuse bleeding thus cannot be avoided at surgery. The large amount of bleeding observed during the surgery of a patient with Castleman's disease in the posterior mediastinum may be due to tight adhesion and hypervascularity of the tumor. Therefore, care should be exercised in choosing the surgical approach if Castleman's disease is suspected in cases of posterior mediastinal tumor.