A retrospective analysis was performed on 36 patients with primary cysts and tumors of the mediastinum seen at the Department of Thoracic and Cardiovascular Surgery of Maryknoll Hospital from January 1983 to December 1993. There were 21 female and 15 male patients in the study. Ages ranges from 2 years to 72 years, with a mean of 34.7. There were 9 malignant tumors and 27 benign tumors.Thymic neoplasms were the most common. For the whole series, 29 of the patients had tumors in the anterior mediastinum. There appears to be an in6rease in tumors in the anterior compartment. There were 30 symptomatic patients in our series. Of the patients with malignant disease, 89 % were symptomatic. All of benign tumors were completely removed and malignant tumors were treated with chemotherapy and radiotherapy after operation. There were 9[27.3 %] postoperative complications. There was no postoperative mortality. Follow-up was available on 27 patients. There was no recurrence, malignant degeneration, or growth of any tumor. It is hoped that careful evaluation and aggressive treatment of mediastinal tumors will continue to provide improvement in the prognosis for these patients.