Thymomas are common anterior mediastinal tumors. In rare instance, thymomas develop in ectopic thymic tissue and are found in various locations in the thorax outside of the anterior mediastinum. They have been discribed in middle mediastinum, within the lung, or in the extrapleural tissue. Intrapulmonary thymoma is a very rare disease and is infrequently documented. The authors described a case of intrapulmonary thymoma in the left lung, which was proved by tranthoracic needle biopsy & operation with pathology. A review of the literature concerning the subject is also given.