One hundred forty-six cases of pulmonary neuroendocrine tumors are assessed according to the classification of Gould and associates and are evaluated for their clinical presentation and subsequent clinical course. Bronchial carcinoids are characteristically found to be central tumors often occurring in comparatively young patients; surgical resection with minimal but clear margins is usually curative. The long-term prognosis is excellent in the majority of patients, although rarely regional nodal and distant metastases develop. Well-differentiated neuroendocrine carcinomas are most frequently peripheral tumors. In stage I and II disease, surgical resection alone is curative and patients with locally advanced tumors may have a prolonged disease-free interval. The overall prognosis is less favorable than that of bronchial carcinoids but considerably better than that of small cell neuroendocrine carcinomas, with which they are still at times confused. Intermediate-sized cell neuroendocrine carcinomas are often wrongly categorized as large cell undifferentiated carcinoma. They have a distinctly aggressive clinical course comparable with that of small cell neuroendocrine carcinoma and should be treated similarly. Small cell neuroendocrine carcinomas are aggressive, rapidly disseminating neoplasms. Even in clinical stage I tumors, patients must be considered to have disseminated metastases. The role of surgical therapy in these two latter tumor types is adjuvant to aggressive systemic chemotherapy.