From 1962 to 1987, 72 patients with primary colorectal cancer underwent surgical treatment for pulmonary metastases. The overall cumulative 5 year survival rate was 41.3%. But the cumulative 1 year survival rate of patients with incomplete resection was 20.0%. Reduction surgery should not be employed. Twenty-nine of 66 patients with complete resection have recurred. The most of first manifested recurrences were in the lung and within 18 months after thoracotomy. This tendency was remarkable in patients with multiple pulmonary metastases and all recurrences of them were within 18 months and 80% were multiple in bilateral lung. Almost all multiple pulmonary metastases seemed to be only one manifestation of generalized metastatic disease. So indication of surgical treatment for them should be cautious. Type of pulmonary resection had no influence on post-thoracotomy survival rate. But in patients with partial resection, 7 recurrences at surgical margin and one recurrence on regional lymph nodes were doubted. Four metastatic lesions less than 3cm in maximum diameter had metastases to the regional lymph nodes. To resect more curatively, lobectomy and systemic lymphadenectomy should be recommended as the standard operation for pulmonary metastases of colorectal cancer.