Thirty-nine patients with bronchioloalveolar carcinoma were reviewed. The primary lung tumor from 27 patients was examined and divided by histological criteria into three categories. The type 1 pattern was associated with a mean survival of 4.7 years. A mean survival of 3.8 years was attained in patients with type 2. Patients with the type 3 pattern had an average survival of 1.4 years. There was a statistically significant difference in survival when types 1 and 2 together were compared with type 3 (rho less than 0.05). Another statistically significant finding was a mean survival of 5.2 years in patients with negative lymph nodes after surgical resection and a 2.2 year mean survival in patients with positive nodes. The tumor histology of bronchioloalveolar carcinoma should be examined carefully to obtain helpful information in predicting survival. We recommend that these tumors be classified as well-differentiated or poorly differentiated bronchioloalveolar carcinoma.